The United States Doesn’t Spend Enough on Its Military

Our future, and the future of our allies, depends on stronger, and yes, more expensive, armed forces.

U.S. marines
U.S. marines in Afghanistan on Oct. 9, 2009.

Photo by Asmaa Waguih/Reuters

At Tuesday’s GOP presidential debate in Milwaukee, Rand Paul railed against Marco Rubio for calling for increases to the military budget: “How is it conservative to add a trillion dollars in military expenditures? You can not be a conservative if you’re going to keep promoting programs that you’re not paying for.” Rubio replied by arguing that “we can’t even have an economy if we’re not safe,” and that “the world is a safer place when America is the strongest military power in the world.” This brief exchange captures a debate that’s been dividing America’s political class for years. Paul is standing in for those, on the left and the right, who believe that the time has come for the U.S. to stop pretending it can be the world’s policeman, and to start shifting money from our military to needs closer to home. Rubio speaks for those in both parties who see U.S. global leadership as more important than ever, and who worry about the erosion of U.S. military power. Both sides make compelling arguments. But in the end, Rubio is right. The United States does not spend enough on its military, and the longer we go without increasing military expenditures, the more dangerous the world is likely to become.

Granted, Rand Paul makes a fair point about at least one thing. The U.S. defense budget is already quite large. In 2015, the U.S. spent $610 billion on the military, making its defense budget the largest in the world by a wide margin. The U.S. spent more on defense than the $601 billion that China, Russia, Saudi Arabia, France, Britain, and India—the countries with the next seven largest military budgets—spent combined. If we limit our comparison to America’s NATO allies, the numbers still look quite stark. The U.S. alone accounts for a whopping 75 percent of the military spending by all of NATO’s 28 current members. Under the two-year budget agreement that the Obama administration hammered out with the Republican leadership in Congress, baseline defense spending will be $548 billion while spending on Overseas Contingency Operations will be $59 billion, for a grand total of $607 billion. That’s hardly chump change. But it’s not enough.

Keep in mind that backing a larger, more formidable military is not the same thing as backing a more hyperactive military. Because our military has been so formidable for so long, there are instances in which U.S. policymakers have resorted to using force when other tools of statecraft might have been just as effective, and at lower cost. Over-relying on military force can have terrible consequences, especially when we don’t have a clear understanding of what we’re using military force to achieve. The point of investing in a more capable military is not to topple foreign governments at the drop of a hat, or to recklessly enmesh U.S. forces in conflicts that will have no meaningful impact on U.S. national interests.

To understand how much we ought to spend on the military, we first need to get a handle on what exactly we want our military to be capable of doing. There is a large and growing gap between what we expect of our military and what it can realistically accomplish, given the resource constraints it faces. Many Americans believe that what we really ought to do is lower our expectations for what our military should be able to accomplish, which in turn would allow the U.S. to spend less. Yet many of the expensive things that the U.S. military does are necessary if we are to live in a more peaceful world—and that is why the U.S. must spend more.

What do we expect of our military? First and foremost, it is the job of the U.S. military to protect the homeland from foreign invasion. That’s a fairly straightforward job, as the U.S. is shielded from powerful rivals by the Atlantic and the Pacific Oceans. In addition to protecting the homeland, the U.S. has long sought to possess what the MIT political scientist has called “command of the global commons.” By the “commons,” Posen means the sea-lanes and the airspace that are so central to global commerce, as well as low Earth orbit, a nearby region of space that is thick with satellites. As Posen explains, command does not mean that the U.S. has exclusive use of the commons, or even that others can’t make use of the commons for military purposes. Rather, it means that if the U.S. felt that it needed to deny the use of the global commons to some rival state, it could so. Moreover, command means that if some rival state were foolish enough to prevent the U.S. from making use of the commons, the U.S. could make them regret they ever tried.

The reason command of the commons is so important is that the U.S. is and has long been a trading nation, and if rival states could deny the U.S. access to the commons, the U.S. would always be at the mercy of these rival states. The U.S. managed to get by when the British Empire had command of the commons in an earlier era, but we have little experience of a world in which access to the commons was controlled by an unfriendly power. One of the chief arguments for the U.S. involvement in the First and Second World Wars was that if some other power grew dominant on the Eurasian landmass, it might then achieve command of the global commons and tie an economic noose around America’s neck. Command of the commons is extremely valuable, yet America has had it for so long that we tend to take it for granted. That is a mistake. And command of the commons is getting more expensive to maintain.

The other thing we expect of our military is that it be able to protect not just the U.S. homeland, but also our allies around the world. The United States is pledged to defend every other NATO member state if they’re ever under attack. To be sure, every other NATO member state has also pledged to defend the U.S. But let’s just say that in practice, the U.S. is not banking on the Estonians to ride to the rescue in case of an invasion while the Estonians are certainly banking on the U.S. having their back if the Russians come knocking. And NATO is just the tip of the iceberg. Michael Beckley, a political scientist at Tufts, has observed that since World War II, the United States has signed defense pacts with more than 60 countries. This U.S.-led global alliance contains 25 percent of the world’s population and generates 75 percent of global GDP. America’s allies have primary responsibility for their own defense, to be sure. Yet they really do count on the U.S. to step up when the going gets tough.

Why does the U.S. extend security guarantees to so many different countries, including rich ones? One way to think about it is that U.S. allies are by definition countries that the U.S. will never have to fight against. Instead of building up their militaries in ways that might threaten the U.S. or their neighbors, former rivals like Germany and Japan have militaries that are almost exclusively devoted to territorial defense. Whereas both Germany and Japan once had imperial designs, neither country could conquer a faraway land if they tried. What they can do is meaningfully contribute to U.S.-led efforts to defend not only their own homelands but also other democracies in their respective regions. The U.S.-led global alliance has created a vast zone in which interstate conflict is largely unknown, and commerce can flow freely. American leadership allows and encourages our allies to cooperate, and it makes it effectively impossible for them to wage war on each other. This is a far cry from the years before 1945, when the world’s richest and most powerful countries were at each other’s throats. Could it be that the remilitarization of Germany and Japan outside of the American security umbrella would be welcomed by their neighbors? Might the Middle East be safer if Saudi Arabia had to fend for itself, and it devoted its oil wealth to, say, building its own nuclear arsenal? I’m skeptical, and frankly I think it would be unwise for us to roll the dice to find out.

For decades, mainstream Democrats and Republicans have agreed that bearing the costs of U.S. global leadership is preferable to the uncertainty that would arise if the U.S. were to pull back, and so the U.S.-led global alliance has persisted. From Bill Clinton to Barack Obama, every president since the end of the Cold War has actually favored expanding this alliance. The problem we face now is that both Democrats and Republicans don’t seem to appreciate that the costs of U.S. global leadership are rising, whether they like it or not.

Consider the case of China. In recent years, China has devoted a growing share of its military resources to so-called anti-access and area denial weapon systems. First, they want to ensure that they can prevent the United States from having free rein throughout the Western Pacific, their backyard, and so they are pouring money into things like cheap missiles that can overwhelm America’s big, slow-moving naval vessels and overseas bases. If China fires off hundreds or thousands of missiles, they only need a handful to reach their targets to deal a devastating psychological blow to the U.S. and its allies. This is very smart strategy, and U.S. defense planners are thinking hard about how to counter it. But the Chinese benefit enormously from the fact that they really just want to dominate their backyard and to ensure that they’re eventually strong enough to keep the U.S. out of it. If the Chinese could do that, they could then dominate their neighbors, including U.S. allies like Japan and South Korea. The U.S. would lose command of the commons in the world’s most economically dynamic region. Chinese domination of the Western Pacific is far from inevitable. To successfully contest it, however, the U.S. will have to spend money.

Why can’t Japan, or other affluent allies, pick up the slack? To be sure, our allies have a role to play. The U.S. military and its partners are involved in a big, complex, cooperative enterprise, in which the U.S. takes on some roles while partner countries take on others. During the Cold War, the U.S. expected its NATO allies to be prepared for ground combat in Europe and its Asian allies to focus on anti-submarine warfare. The U.S. was concerned primarily with maintaining its large nuclear weapons arsenal and maintaining command of the commons. Since the Cold War, Tufts’ Beckley has identified a broadly similar division of labor. As before, the U.S. focuses on commanding the commons and maintaining high-end offensive capabilities. Now, however, America’s European allies are more likely to engage in peacekeeping and post-conflict stabilization while our Asian allies are devoting resources to countering China’s new anti-access and area denial weapons. With the notable exception of Iraq, a war that many U.S. allies wanted no part of, it is not at all uncommon for U.S. allies to take more casualties as a share of their ground forces than the U.S. in post-conflict missions. To put it crudely, the U.S. military is built to focus on the high-intensity phase of a conflict in which the goal is to overwhelm the enemy with superior firepower. U.S. allies are more suited to doing the often equally important work of post-conflict stabilization.

None of this is to suggest that America’s European allies shouldn’t spend more on their militaries. They should. NATO has set a 2 percent target for defense spending, and only five NATO members clear that very modest threshold. But even if Britain, France, and Japan doubled or tripled their military budgets, they still couldn’t afford to command the global commons or successfully defeat enemy forces in serious ground combat. Like it or not, the U.S. really is the indispensable nation. 

Over the past decade and a half, the U.S. has been embroiled in counter-insurgency operations in Iraq and Afghanistan, and it has played a supporting role in counter-insurgencies in a number of other countries as well. Counter-insurgencies are a textbook example of the kind of mission the U.S. ought to avoid if possible. Unfortunately, the U.S. needs to be prepared for counter-insurgencies, as countries can’t always pick and choose the wars they fight. As the global population grows more urban, and as the threat of state collapse continues to grow more pressing than the threat that one state will openly invade another, it is all but certain that the U.S. and its allies will be called upon to restore order.

And restoring order is extremely expensive, because restoring order can’t be done by drones. High-tech weapons can work wonders when your goal is to wipe out your enemy. But if your goal is to win over a population, and to carefully distinguish between friends and enemies who can be hard to tell apart, you can’t just rely on high-tech weapons—you need intelligent people, including intelligent people who speak the local language, who are capable of making friends and influencing people. In an ideal world, it would be our allies who could take on these tasks. The trouble is that counter-insurgency and peacekeeping aren’t the same thing. Counter-insurgency requires that you have a full complement of capabilities, from the heavy firepower you need to decisively win a conflict to the soft skills you need to avoid a conflict in the first place. Peacekeeping is what you do when peace has already been established. Part of the reason the U.S. needs to spend more on its military is that the U.S. needs well-trained women and men with the skills and the talent to handle chaotic situations, and they need the best tools money can buy.

The world is a dangerous place, but it is far less dangerous than it would be in the absence of a uniquely powerful United States. The technologies that have propelled America’s military dominance over the past few decades have grown cheaper and more widespread, and they’ve increasingly fallen into the hands of America’s enemies. If history is any guide, the U.S. will allow its military edge to deteriorate until some rival power delivers its military a humiliating blow, at which point Americans will be forced to scramble to reverse course, under highly unfavorable circumstances. We have it in our power to do things differently—to deter threats before they arise, and to help ensure that the world won’t descend into the great power rivalry that gave us World War I and II. Those who say that we can’t afford to spend more on our military have it backward: We can’t afford not to invest in the peace and security that are the product of U.S. global leadership, and on which billions of people around the world depend. If the only way we can afford higher military expenditures is by raising taxes, so be it.