What NATO Countries and Other U.S. Allies Contribute to the Collective Defense


Jul 5, 2024

Soldiers and armored vehicles are staged for the opening ceremony for exercise Saber Guardian 23 in Smardan, Romania, May 29, 2023, photo by Capt. Avery Smith/U.S. Army

Soldiers and armored vehicles are staged for the opening ceremony of exercise Saber Guardian 23 in Smardan, Romania, May 29, 2023

Photo by Capt. Avery Smith/U.S. Army

The time had come for some blunt words. Defense Secretary Robert Gates assured his European audience that he was speaking “in the spirit of solidarity and friendship.” Then he brought down the hammer.

NATO had become a “two-tiered alliance,” he warned. The United States and a few other countries were paying the bills and bearing the risks. The rest needed to step up. Otherwise, he said, the alliance would face the “very real possibility of collective military irrelevance.”

The BBC described his 2011 speech as a warning shot. A British analyst called it a cold shower. But really, it was the same message American officials had been delivering to their European allies for most of NATO's 75-year existence. In short: Pull more weight.

Researchers at RAND have now published a country-by-country index that shows, in much greater detail than previously available, what each ally brings to the collective defense. The results surprised even them. The United States is still by far the biggest contributor—but it's not as lopsided as it might seem. “The picture is a lot more complicated,” said King Mallory, a senior international defense researcher at RAND.

One number has come to dominate the debate over who pays what at NATO: 2 percent. That's how much each ally has pledged to spend on defense as a share of its economy. Eighteen of NATO's 32 member states are on track to hit that target this year, up from 11 last year, up from 5 when Gates delivered his speech.

Almost every NATO country in Europe has ramped up its defense spending as it watches Russia brutalize Ukraine.

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Former president Trump said earlier this year that he would encourage the Russians to “do whatever the hell they want” to countries that don't pay their share. But other administrations, Republican and Democrat, have also pushed allies to spend more. President Biden said last year he was working to ensure allies “spend enough on their defense, the 2 percent.” Former president Obama told an interviewer in 2016 that “free riders aggravate me.”

But that 2 percent number has never been a great metric. A country could spend tens of billions of dollars on combat boots and clear that threshold without really making the world any safer. “There's a lot of bluster, but what can you really do with that 2 percent number?” Mallory asked. “You can't really make any kind of policy decisions with it. We wanted to come up with a more objective way to measure this, to get at the real truth.”

He and a small team of researchers at RAND collected data on how many troops, tanks, and tactical aircraft each country has. They counted every satellite, every submarine, every drone, helicopter, and piece of artillery. They factored in overall spending levels, but also the cost of peacekeeping missions and the exports lost to enforcing sanctions.

When they were done, they had an index that shows not just how much each country spends, but what it can actually bring to the table in time of war. The researchers included all NATO countries, as well as several Asian countries that also have collective-defense treaties with the United States. Their effort, sponsored by the Office of the Secretary of Defense, wrapped up in 2019. Its public release was put on hold, in part because of COVID and staff turnover at the Pentagon.

How the Index Works

Share of Burden

  • Inputs
    • Defense financial inputs
      • Military expenditures
      • Major equipment expenditures
    • Nondefense financial inputs
      • Peacekeeping operations
      • Share of lost exports
  • Outputs
    • Preparedness
      • Personnel
        • Active-duty forces
        • Join command staff
      • Ground forces
        • Main battle tanks
        • Mechanized vehicles
        • Helicopters
        • Artillery
        • Quality of ground forces [gray italics]
      • Air forces
        • Tactical aircraft
        • Airborne early warning aircraft
        • Tanker aircraft
        • Transport aircraft
        • Quality of air forces [gray italics]
      • Naval forces
        • Aircraft carriers
        • Tactical naval aircraft
        • Tactical submarines
        • Anti-submarine warfare aircraft
        • Capital ships
        • Heavy amphibious ships
        • Quality of naval forces [gray italics]
      • Military mobility
        • Strategic airlift aircraft
        • Strategic sealift tonnage
        • Freedom of movement
      • C4ISR
        • Satellites
        • ISR aircraft
        • Airborne early wanring aircraft
        • Heavy unmanned aerial vehicles
    • Deployments
      • Contributions to ongoing operations
        • Share of deployed forces

NOTES: This is a simplified look at how the Burdensharing Index works. Read from left to right, it’s like clicking open folders and then subfolders on a computer desktop. Outputs, for example, include measures of military preparedness and active deployments. Preparedness includes all personnel or ground forces, which are further divided into specific capabilities, like main battle tanks or helicopters. C4ISR = command, control, communications, computers, intelligence, surveillance, and reconnaissance; ISR = intelligence, surveillance, and reconnaissance. Items in gray italics are not yet included in the index.

The index shows the United States bearing around 47 percent of the total burden. No other ally came close—but that was actually less than commonly assumed. The researchers, like many U.S. officials, expected the number to be well past 50 percent. It has almost certainly fallen even lower in the past few years. Almost every NATO country in Europe has ramped up its defense spending as it watches Russia brutalize Ukraine.

Organization Share of Defense Burden Share of Alliance GDP
NATO 36 42
Asia 17 22
United States 47 35

NOTE: Because of rounding, totals might not sum exactly to 100.

But some small countries could push their entire economies into defense and still not be major contributors at the global level. To account for that, the researchers took their top-level findings and divided them by each country's ability to pay. That gave them a single score, a burdensharing ratio. Anything over 1.0 meant a country was contributing at least its fair share.

The United States scored 1.32. Six NATO allies, mostly small countries in south and central Europe, scored higher. Nine other allies scored above or just below the 1.0 cutoff. That left 20 countries in Europe and Asia that could be called upon to contribute more. They included a wealthy major ally and six countries that neighbor either Russia or China.

RAND's report doesn't name them. That's partly because the numbers are out of date, and partly because shaming countries that could do more was never really the point. The index is meant to allow U.S. and NATO leaders to identify shortfalls in what they need and then make targeted requests to the countries best suited to address them.

A country might have a low overall score, for example—but a relatively high score in one specific capability, like tanker aircraft. Those will be valuable in almost any future conflict. NATO could push that country to not just increase its spending, but to invest the money in doing what it does best, building tankers. NATO could also call on lower-scoring countries to take the lead on entirely new capabilities, like advanced drones.

The index is meant to allow U.S. and NATO leaders to identify shortfalls in what they need and then make targeted requests to the countries best suited to address them.

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“It's a way to structure those conversations more productively,” said Jonathan Welburn, a senior operations researcher who helped build the index. “When you look at it through this analytical, mathematical lens, you get a much cleaner and clearer understanding of what the next steps should be. It gives you something you can actually act on.”

There's one other missing piece here.

A country could pour billions of dollars into its air tanker industry—but that still doesn't tell you how those tankers or their pilots will perform under fire. For that, the researchers developed a survey. It asks experts, such as field commanders or intelligence analysts, to rate each country's air, sea, and ground forces. The results can be fed into the index to provide a real-world check on just how ready each country is to contribute.

RAND published the index in May. One copy went to the chairman of the Joint Chiefs of Staff. Another went to the National Security Council. The Senate Armed Services Committee also requested and received a copy.

The index may have been delayed, but it came out at an especially important moment. The United States has been pushing Europe to do more—and threatening to scale back if it does not—since at least the 1950s. Former Defense Secretary Robert Gates may have been blunt in his 2011 speech, but he was even more blunt in his 2014 book, Duty: Memoirs of a Secretary at War. Telling some countries to increase their spending, he wrote, was “about as useful as shouting down a well.”

But things have changed.

“What makes allies increase their contribution levels is when something major shifts in the international landscape," Mallory said. “We are right in the middle of that right now, with Russia in Ukraine and China bullying its neighbors. This is probably the best time there's going to be to encourage allies to make bigger, more-effective contributions to help the greater alliance.”

There's one other reason to think carefully about what countries are really contributing to the collective defense, he added. “It's important to get some rigor and make sure we're measuring these things properly,” he said, “because this is probably going to be a campaign issue in November.”