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Research Brief

U.S. allies and partners in the Indo-Pacific would play central roles in any regional campaign to deter aggression from the People's Republic of China (PRC). Not only would the allies and partners bring their own important capabilities to defend their own territories, but access to their territories, airspaces, and waters would be vital for the U.S. prosecution of any such campaign. This access would be particularly important for the U.S. Air Force (USAF), which would likely rely on access to allied and partner airspaces and bases in the region to counter the PRC.

A pilot walks toward a lineup of F-16 Fighting Falcons before a flight at Clark Air Base, Philippines. Photo by Airman 1st Class Sebastian Romawac/Pacific Air Forces Public Affairs

Photo by Airman 1st Class Sebastian Romawac/Pacific Air Forces Public Affairs

The USAF and the U.S. Department of Defense (DoD) have invested substantial time and effort in increasing the access of U.S. forces to allied and partner territories in the Indo-Pacific region during peacetime, but the extent to which this peacetime access would translate into conflict-phase access is unclear. Both the physical and political geography of the region limit U.S. options for access to such an extent that some allied and partner decisions regarding conflict-phase access could determine the outcome of a conflict.

For these reasons, ensuring access to the territories of allies and partners in the Indo-Pacific in the event of a future conflict with China is a critical concern for U.S. policymakers. A clearer understanding of how and why U.S. allies and partners are likely to make conflict-phase access decisions, and what U.S. policymakers can do to affect those decisions, is therefore essential.

To assess what the United States and the USAF can do to affect these decisions, a RAND Corporation team reviewed the literature on conflict-phase access decisions, surveyed relevant historical case studies, built a framework of how states make those decisions, and applied the framework to five U.S. allies and partners in the Indo-Pacific region: Japan, the Philippines, Singapore, Indonesia, and India. This application involved a deep-dive investigation of the strategic outlook, internal politics, and economic incentives of each nation, including interviews with experts and government officials in the United States and the allied and partner nations. The RAND team then developed a typology of the full range of potential policy levers that the United States could use to shift allied and partner access decisions and identified the levers that would be most promising to improve the chances of gaining conflict-phase access to each country.

The findings should limit expectations about the influence that U.S. policies can have on allied and partner conflict-phase access decisions. In many cases, such decisions are likely to be considered tantamount to going to war against the most powerful state in the region and, thus, are likely to be driven by the highest-level strategic calculations of each country's most vital national interests. U.S. policymakers should understand up front that changing these calculations will not be easy. U.S. policymakers should not expect large or dramatic changes in the host-nation calculations to follow smaller or limited U.S. policy initiatives. Neither should U.S. policymakers expect improvements in peacetime access to necessarily carry over to conflict-phase access. Nonetheless, there are some policies that can improve the likelihood of conflict-phase access being granted. These policies typically focus on addressing specific allied and partner concerns.

This brief summarizes how the five U.S. allies and partners in the Indo-Pacific region that this research assessed are likely to make their conflict-phase access decisions, based on the factors likely to be most influential in informing each decision. The brief then identifies the U.S. policy levers that are most promising for potentially shifting the allied and partner calculations toward approving U.S. conflict-phase access requests. Finally, the brief offers recommendations for U.S. policymakers at three levels: the U.S. government broadly, DoD , and the USAF.

How Do U.S. Allies and Partners Make Conflict-Phase Access Decisions?

When deciding whether to approve conflict-phase access requests, leaders of states are likely to ask themselves five questions. These questions incorporate strategic, economic, political, and diplomatic considerations and reflect how states in general tend to approach such requests. How leaders answer these questions is likely to determine how they will respond to any access requests from the United States during a potential future conflict:

  1. Would granting access affect the leader or the regime's political survival?
  2. Would granting access affect the country's security directly?
  3. Would granting access affect the outcome of the conflict?
  4. Would granting access affect — or be affected by — similar regional decisions?
  5. Would granting access affect the economic prosperity of the country?
U.S. Air Force Staff Sgt. Kathrine Ancheta marshals U.S. Air Force Capt. Dakota "Dodger" Benge in an F-16 Fighting Falcon during Cope West 21 at Roesmin Nurjadin Air Force Base in Pekanbaru, Riau, Indonesia, June 16, 2021. Photo by Staff Sgt. Matthew Kakaris/USAF

Photo by Staff Sgt. Matthew Kakaris/USAF

These questions are broadly applicable to all states facing the prospect of deciding whether to approve conflict-phase access requests. The RAND team explored the factors most likely to affect the decisionmaking when the five Indo-Pacific countries ask themselves these five questions. The most important factors for each country are as follows:


Japanese reliance on the U.S. security umbrella: Japan's perception that its alliance with the United States is the fundamental guarantee of its security is likely to strongly influence its conflict-phase access decision. There are substantial fears in Japan that refusing U.S. conflict-phase access requests, including access to existing U.S. bases, could undermine the alliance and risk forcing Japan to confront China on its own.

U.S. dependence on Japanese bases: Japan assesses that U.S. success in many Indo-Pacific scenarios, particularly those involving Taiwan, would require U.S. access to U.S. bases in Japan. Should Japan refuse this access, it would substantially hamper U.S. efforts, likely worsening long-term Japanese security in the process.

The Philippines

Risk of retaliation from China: A Philippine assessment of the potential scope of Chinese retaliation, both military and economic, would factor heavily into a conflict-phase access decision. Philippine leaders are concerned about the vulnerability of their territory to Chinese attack, particularly in the South China Sea. Economic retaliation is even more of a concern because the Philippine economy, being so tied to Chinese trade and investment, is quite vulnerable to PRC economic coercion.

Philippine assessment of the likelihood that the United States will defend Philippine territory: Philippine uncertainty over whether the United States will defend Philippine territory if China attacks, particularly in the South China Sea, is likely to influence a Philippine access decision. The Philippines would also consider whether refusing access might degrade the U.S.-Philippine alliance and thereby reduce the likelihood of the United States defending Philippine territory in the future.


Singapore's concern over losing its status as a regional economic hub: For Singapore's policymakers, economic prosperity is inextricably linked to both the survival of the political regime and the national security of the nation. If Singapore granted access in a potential U.S.-China conflict, China could devastate Singapore's position as a regional economic hub that offers a safe, efficient, and trustworthy place in which to make exchanges.

Necessity of U.S. balancing role in the region to safeguard Singapore's autonomy: Singapore seeks to maintain foreign policy autonomy and avoid becoming too close to or too dependent on any single power. But Singapore's hedging is informed by a general preference for the United States as the guarantor of order, prosperity, and security in Southeast Asia. Singapore would consider whether refusing access would lead to a U.S. defeat in a potential conflict, which would leave the island-nation vulnerable to a regional order dominated by an assertive China.

Singapore's strong commitment to and reliance on the rule of law and the current regional order: As a small state in a dangerous neighborhood, Singapore relies on the rule of law and the current regional order to safeguard its interests. An order driven more by the whims of larger, more-powerful states could leave Singapore exposed to attack or coercion. Singapore may thus be more amenable to granting access to prevent larger states from using force to violate the principles of sovereignty and territorial integrity.


Indonesia's nonalignment policy: Indonesia views its nonalignment policy as the best way to keep the country secure by maintaining neutrality and addressing security challenges multilaterally through the Association of Southeast Asian Nations (ASEAN). A strong preference among Indonesian elites to maintain a nonalignment policy even during a conflict would factor heavily into Indonesia's access decision.

Risk of retaliation from China: Indonesian policymakers are concerned about military and economic retaliation from China. As for military retaliation, a primary concern is the vulnerability of the Natuna Islands to a Chinese attack. Indonesia's economy is very vulnerable to economic retaliation, given the amount of Indonesia's trade and investment with China, which is significantly greater than Indonesia's trade with the United States.

Whether ASEAN supports U.S. operations: Indonesia would consider the stance of ASEAN members in making its decision. Although ASEAN would be unlikely to form a consensus regarding a U.S.-China conflict, Indonesia's position as the head of ASEAN and its preference to work through ASEAN on regional issues would carry weight with Indonesia's policymakers. Indonesia would likely look to ASEAN to assess the level of support for the United States in a conflict with China before deciding whether to grant access.


Indian policymakers' extreme caution and risk aversion vis-à-vis China: India would hesitate to take actions it perceives would antagonize China. India recognizes that China is too economically and militarily powerful for India to prevail in any sustained confrontation with it. Indian policymakers would fear that granting conflict-phase access to the United States would lead to full-scale war with China or, at least, provoke a PRC reaction sufficiently dangerous to warrant caution.

India's traditional reluctance to join any sort of military alliance: India regards formal alliances, informal security cooperation blocs, or even any partnership that might be characterized as "alignment" as detrimental to its sovereignty and national interests. Indian policymakers believe the nation's core interests are best served by a foreign policy that balances competing nations against each other and maintains Delhi's freedom of action. U.S. policymakers should not underestimate the depth and endurance of this worldview.

U.S. Air Force and Indian Army members receive a crew brief prior to boarding a C-130J Super Hercules assigned to the 143rd Airlift Wing, Rhode Island Air National Guard. Photo by Capt. Mark Lazane/Pacific Air Forces Public Affairs

Photo by Capt. Mark Lazane/Pacific Air Forces Public Affairs

What Policy Levers Are Likeliest to Raise the Chances of Conflict-Phase Access?

The RAND team next analyzed what policy levers, if any, could allow U.S. policymakers to shift the access calculations. The team reviewed the policy levers that the United States could use to expand its influence among allies and partners in general terms and then identified the levers most applicable to affecting each conflict-phase access decision in each potential host nation.

The team then assessed which levers could most plausibly affect the conflict-phase access decisions that the five countries make, given their most important deciding factors, as outlined in the previous section. This assessment evaluated both whether and to what extent peacetime policies could influence conflict-phase access decisions. Table 1 highlights the U.S. policy levers most likely to improve the likelihood of the United States being granted conflict-phase access to each country, given its key deciding factors.

Table 1. Most Important Deciding Factors Matched with U.S. Policy Levers Most Likely to Be Effective

Country Most Important Deciding Factors U.S. Policy Levers Most Likely to Be Effective
  • Japanese reliance on U.S. security umbrella
  • U.S. dependence on Japanese bases
  • Expand and deepen high-level discussions of joint wartime contingency planning
  • Increase intelligence-sharing with Japan
  • Publicly and privately reiterate the U.S. commitment to Japan's defense across all contingencies
  • Expand preparations for cooperative cyber defense and information resilience, air and missile defense, and defense against attacks on distant Japanese islands
  • Philippine assessment of the likelihood that the United States will defend Philippine territory
  • Risk of PRC retaliation
  • Provide an explicit security guarantee to protect territory claimed by the Philippines in the South China Sea
  • Increase high-visibility commitments to Philippine security
  • Dramatically expand U.S.-Philippine economic ties
  • Singapore's concern over losing its status as a regional economic hub
  • Necessity of U.S. balancing role in the region to safeguard Singapore's autonomy
  • Singapore's strong commitment to and reliance on the rule of law and regional order
  • Reenter the Trans-Pacific Partnership (U.S.)
  • Regularize expanded peacetime access requests in Singapore
  • Regularize expanded peacetime access requests elsewhere in Southeast Asia
  • Conduct high-level consultations to clarify potential conflict-phase access requests in advance
  • Build consensus against PRC aggression within international or regional organizations
  • Indonesia's nonalignment policy
  • Risk of retaliation from China
  • Whether ASEAN supports U.S. operations
  • Build consensus against PRC aggression within international or regional organizations
  • Strengthen U.S. ties with ASEAN
  • Indian policymakers' extreme caution and risk aversion vis-à-vis China
  • India's traditional reluctance to join any sort of military alliance
  • Build consensus against PRC aggression within the United Nations General Assembly and the Quad
  • Gradually regularize peacetime access requests
  • Conduct high-level consultations in advance of a conflict regarding anticipated access requests
  • Expand cooperation regarding defense equipment production and related technology transfer

Across the five countries, ranging from those with high levels of military cooperation with the United States (such as Japan) to those with very limited current relationships (such as Indonesia), the analysis found that new or altered U.S. government policies are likely to have relatively limited effects on decisions to grant the United States access during a conflict. That said, the analysis did identify three main areas in which U.S. policies could make marginal differences in multiple countries, as well as a fourth area of larger U.S. policy changes that could make a difference across the board (as shown below).

Four Most Promising U.S. Policy Categories

  1. Preplanning and regularizing access requests: Requesting and regularly using, in advance, the same types of access that the United States is likely to request in a conflict can help shape both the host-nation and PRC perceptions of which access requests are routine and which could increase the risk of PRC retaliation. Regularized access and operations can also enhance perceptions within host nations of a U.S. commitment to their defense, which may in turn increase their willingness to face PRC retaliation during a conflict. This policy likely applies only to lower-level types of access, such as overflight or logistics, and only to certain states.
  2. Offering greater commitments to and holding consultations with potential host nations: Several potential host nations remain uncertain whether or in what circumstances the United States will fight to defend them. Public and private statements, high-level discussions about how a conflict with China might be prosecuted and how the host nations might participate, and other demonstrations of U.S. commitment can increase the willingness of states to risk PRC retaliation by providing U.S. access.
  3. Building regional consensus: Regional and international attitudes and consensus on the importance of opposing potential Chinese aggression can be highly influential in shaping the access decisions of U.S. allies and partners. Such a consensus can be established primarily through U.S. diplomatic levers and initiatives and secondarily through U.S. military engagements with a broad range of allies and partners in the region and beyond.
  4. Enacting larger U.S. policy changes: Although most policies described here have limited scope and can be pursued under the current U.S. approach to the region, other policies would require broader changes in the U.S. approach. For example, experts and officials from multiple Indo-Pacific countries said that rejoining the Trans-Pacific Partnership was the type of shift in U.S. economic engagement that could offer the region a more credible economic counterweight to China and reduce concerns about PRC economic retaliation. Unfortunately, such larger-scale policy shifts do not appear to be under consideration in Washington, and the limited expectations noted here are, in part, a function of the low probability of such shifts. If senior U.S. policymakers become willing to make larger changes in U.S. policy toward the region, the U.S. potential to alter conflict-phase access calculations could expand as well.
A team of Japanese Air Self-Defense Force members prepare for a specialized fuel operation on a C-130 Hercules at Yakumo Sub Base, Japan. Photo by Airman 1st Class Amanda Jett/Air Mobility Command Public Affairs

Photo by Airman 1st Class Amanda Jett/Air Mobility Command Public Affairs


The findings led the RAND team to offer the following policy recommendations for the U.S. government, DoD, and the USAF:

For the U.S.Government

  • Consider clarifying or expanding security guarantees for allies and partners uncertain of the U.S. defense commitment: Several countries are uncertain of the extent of the U.S. commitment to defend their territories in the event of Chinese retaliation during a conflict. Clarifying or reiterating U.S. security guarantees or expanding the guarantees specifically to cover vulnerable territories might increase the willingness of these states to face PRC retaliation if they were to grant U.S. forces access in a conflict.
  • Provide a credible regional economic counterweight to China: U.S. allies and partners in the region are vulnerable to Chinese economic retaliation and lack confidence that the United States will support them economically in a way that will reduce this vulnerability. Altering this dynamic would require large changes in U.S. policy, such as U.S. reentry into the Trans-Pacific Partnership or a similar economic arrangement — and not just modest increases in direct assistance or investment. Committing to a larger U.S. economic role in the region could reduce the risks associated with Chinese threats of economic retaliation and increase the likelihood of conflict-phase access being granted by countries concerned with these risks.
  • Work to build regional consensus against Chinese aggression: The level of regional consensus supporting the United States and opposing China in a conflict is an important factor for several regional states. The U.S. government should continue to work with ASEAN members to build consensus on the risks to regional security of PRC aggression and the benefits of collective opposition to it. The engagements should extend beyond the allies and partners who would receive U.S. requests for conflict-phase access because the calculations of those states would likely be affected by reactions throughout the region.

For DoD

  • Expand high-level discussions of likely U.S. access requests in a future contingency: DoD already discusses potential conflict-phase access requirements and potential requests with Japan. These conversations should be extended to other allies and partners. While the degree of specificity could vary across states, the conversations would lay the foundation for the potential expansion of existing peacetime access agreements and would set expectations that could, in turn, raise the likelihood of approvals of U.S. requests.
  • Increase intelligence-sharing with allies and partners and increase cooperation with them on cyber defense and information resilience: Expanding the scope of DoD intelligence-sharing and DoD cooperation on cyber security and resilient information networks could help the United States cultivate trust with regional states, build consensus against Chinese aggression through increased situational awareness of PRC activities in these domains, and reassure allies and partners of U.S. capabilities and commitments to their defense. The level of intelligence-sharing and of cyber and information cooperation would differ based on the U.S. relationship with an ally or partner and on its capabilities.
  • Regularize expanded peacetime access requests: Regularizing peacetime access requests could reduce the risks of similar conflict-phase access requests being denied. The types of requests considered to be normal in peacetime could shape both host-nation and PRC assessments of what might prompt PRC retaliation in a conflict. Routine requests would likely not include requests to conduct combat operations from an ally's or partner's territory, but making lower levels of access requests relatively routine could increase the likelihood of their approval during a conflict.
  • Reinforce commitments to allies and partners: Visible U.S. actions that reinforce U.S. defense commitments — such as military exercises and training, high-level DoD visits, arms sales of requested systems, and public messages reiterating the commitments — can reassure states that the United States is committed to defending them if they face PRC retaliation for having granted U.S. conflict-phase access requests. These signals of U.S. commitment would need to be tailored to the state in question. For U.S. treaty allies, such as Japan and the Philippines, the signals could likely be public and definitive. Other states, such as India, may prefer less-public signals of commitment.


  • Increase the frequency and regularity of USAF requests for lower-level but operationally essential allied and partner access: Identifying the types of lower-level access, such as for overflight or logistics, likely to be valuable in a contingency and then routinizing such USAF requests can increase the likelihood of their being granted during a conflict, at least in certain countries. Again, the benefits of routinization are unlikely to extend to higher-level access requests, but increasing the likelihood of lower-level access can still prove important.
  • Focus USAF activities in the region on demonstrating U.S. commitment and enhancing capabilities for combined operations with allies and partners, rather than building independent allied or partner capabilities: From combined exercises to rotational deployments, USAF activities can send clear signals of the broader U.S. commitment and ability to defend allies and partners — important factors in convincing allies and partners to provide conflict-phase access to U.S. forces. In contrast, a focus on enhancing allied and partner capabilities to operate independently of the United States risks signaling that Washington expects the allies and partners to fight on their own in a confrontation with China.
  • Prepare to cooperate with allies and partners on their defense against a wider range of contingencies: USAF operational concerns in the Indo-Pacific appear to concentrate increasingly on a small number of potential contingencies, most notably a conflict over Taiwan. But many allies and partners are concerned about a broader set of security issues and may interpret a narrow U.S. focus on Taiwan as indicating that the United States is not committed to their security more broadly. Preparing to assist allies and partners with a wider range of challenges and doing so in a collaborative manner could reduce concerns that the United States might not be prepared to assist against other types of threats.

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