Both liberal and conservative critics of Donald Trump's foreign policy believe that the US president has done enormous damage to America's array of global alliances. It's easy to understand why: Trump has repeatedly questioned the value of NATO; picked senseless fights with democratic leaders in Europe, Asia, and North America; and, more recently and controversially, betrayed the Kurds. The Economist believes the damage "will take years to mend" and warns darkly that "these concerns represent the unravelling of the order that America worked hard to build and sustain in the decades since the second world war."
Crucial to this indictment is a rarely examined assumption: the belief that every one of the United States' current commitments is a vital national asset and that all its present allies and partners are equally deserving of steadfast US support. But surely this is not the case, for not all allies are created equal, and the value of any commitment is likely to wax or wane over time.
To be sure, having the right allies can be extremely valuable in some circumstances. During the Cold War, for example, the US alliance network exceeded (and in economic terms, dwarfed) the Soviet bloc in population, gross national product, total military manpower, and annual defense spending. The combined strength of the US alliance network is not the only reason the United States triumphed over its Soviet adversary, but it certainly helped. Looking ahead, it is hard to see how the United States could balance a rising China and limit Beijing's capacity to project power around the world without close and effective partnerships with a number of countries, especially in Asia.
Alliances are not an unalloyed good, however, because they also involve costs and obligations. Depending on the precise nature of the commitment, alliances may create new military missions and thus increase one's defense requirements—especially if the ally is far away or hard to defend—and alliance obligations may constrain a country's foreign-policy autonomy in other ways. The Obama administration was reportedly reluctant to confront Saudi Arabia over its conduct in Yemen, for example, because it feared doing additional damage to a relationship already strained by the nuclear deal with Iran. Sometimes, even allies of long standing can become more trouble than they are worth.
For this reason, wise countries choose their allies carefully and do not treat any of them as sacred or inviolable—no matter how ardently leaders defend the relationship in public. As the writers Doug Bandow and Christopher Preble recently reminded us, an alliance is merely a means to an end (typically greater security) and not an end in itself. Unfortunately, US foreign-policy pundits all too often fetishize nearly all of America's current partnerships—both formal alliances such as NATO and less formal security arrangements with dozens of other countries—implying that any diminution in these ties constitutes a dangerous waning of US "influence."
Which brings us to the obvious question: What makes for a good ally? What are the qualities that make a foreign power an especially valuable partner and therefore justifies a US security commitment?
Here's a quick list for you to ponder.
Ideally, a good ally is economically strong and military capable, or it controls other strategic assets such as natural resources or a key strategic location, so that it can contribute meaningfully to the overall strength of the alliance. As noted above, the United States won the Cold War in part because it had powerful, wealthy, and militarily capable states such as Japan, Germany, France, and the United Kingdom on its side, while the Soviet Union only had help from relatively weak and captive satellites in Eastern Europe or overseas dependencies such as South Yemen and Ethiopia. (NATO's European members have let their defense capabilities atrophy badly in recent decades, but they had impressive military forces during most of the Cold War.) North Vietnam was a better partner for Moscow than South Vietnam was for Washington, but on the whole, the US alliance system was much stronger than theirs.
A good ally is politically stable, so that you don't need to spend a lot of time or money propping it up or trying to make sure its internal politics don't go south. And other things being equal, a good ally is not so vulnerable that defending it is almost impossible. Obviously, a state that faces no external dangers has little need for allies, but, ideally, one should prefer allies that aren't about to collapse or in constant danger of being overrun.
Almost by definition, a good ally has interests that are roughly compatible with one's own. For example, the United States does not want any single power to dominate the oil-rich Persian Gulf, and—guess what?—neither does any of its partners there. No two states have identical interests, but the more that interests diverge, the less valuable or viable an alliance will be. As I've noted previously, that is why the US partnership with Syrian Kurdish forces was bound to end eventually. The United States joined forces to destroy the Islamic State's so-called caliphate, and once that task was accomplished, the US commitment was bound to wane.
If interests diverge sufficiently, an alliance will become irrelevant and moribund and may even turn into a serious rivalry. The United States backed Saddam Hussein during the Iran-Iraq War only to turn against him when that war ended and Iraq turned on Kuwait and seemed bent on dominating the Persian Gulf. Similarly, the United States and China were tacit allies against the USSR during the 1970s, but China's rise and the Soviet collapse have brought a steady rise in Sino-American tensions.
Alliances may also elicit cooperation even when short-term interests do not overlap very much. A very good ally is one that will back you even when its own short-term interests are not directly engaged, because it values the overall relationship or because its citizens feel a sense of shared identity. Australia entered World War I even though Germany posed little direct threat to its own security, and it has sent troops to fight alongside US forces in Korea, Vietnam, Iraq, and Afghanistan despite the lack of a "clear and present danger" to Australia itself.
An ally's value is not just a function of interests and capabilities, however; it may also depend on how it treats its partners. A good ally doesn't interfere too much in one's own domestic politics and doesn't overtly favor one political faction over another. A good ally is (mostly) truthful and doesn't lie to you or deliberately feed faulty information to your intelligence agencies. All nations spy on one another to some extent, but a good ally doesn't do so with abandon. Needless to say, a good ally doesn't cut deals with your biggest rivals and isn't constantly hunting for a better deal from some other patron.
Allies that violate one or more of these strictures are more problematic partners. That does not necessarily mean that the alliance should be terminated, but the net value of an otherwise useful ally will decline if it becomes unstable, repeatedly gets into trouble and has to be bailed out, becomes weaker with time and requires more and more protection (see under: Austria-Hungary before World War I), makes promises and doesn't keep them, and repeatedly flirts with one's rivals. The more that such behaviors become commonplace, the more the alliance's value should be questioned.
Based on these criteria, how might we rate some of Washington's current partners? Its NATO allies score well in terms of political stability and economic strength, and, with occasional exceptions, they have been remarkably deferential to US whims—mostly because they still crave US protection. But NATO's members score poorly on military capability, having let their own forces atrophy in recent years, and some of them (e.g., the Baltic states) are hard to defend. On balance, adding them to the alliance made it weaker, not stronger. A number of NATO members have been willing to join in the United States' recent overseas misadventures, although their contributions have been more symbolic than substantive. (It is true that some NATO allies fighting in Afghanistan have lost more soldiers per capita than the United States has, but the United States still supplied the bulk of the military forces there.)
Most of America's Asian partners are politically stable and economically prosperous, but they are weaker militarily than they should be. That situation is beginning to change, however, as a direct response to China's rising power and ambitions. Reasonable people can disagree about the actual threat that China poses and debate whether preventing it from becoming a so-called regional hegemon is a vital US interest or not, but any US effort to prevent a Chinese push for regional dominance will require extensive cooperation with a number of key Asian states. Moreover, many of America's Asian partners are democratic and do not interfere excessively in US domestic politics. For these reasons, their strategic importance is increasing.
Rather obviously, it is America's Middle East partners that are most problematic. Israel scores well in terms of military prowess, which is why it was a valuable ally during the Cold War, but it stayed on the sidelines during both Iraq wars—and had to get extra US protection against Iraqi Scud missiles during the first one. Its interference in US domestic politics is well known and has taken on a more partisan air in recent years, and Benjamin Netanyahu's government has worked overtime to drag the United States into a military confrontation with Iran. Israel also eats up enormous bandwidth in the US foreign-policy debate, engages in extensive espionage activities in the United States, and has policies toward its Palestinian subjects that have long been at odds with US democratic ideals.
Washington's commitment to Saudi Arabia is equally if not more problematic. Riyadh buys a lot of US weapons but cannot use them effectively, and it remains dependent on US support and protection. Its oil remains a key strategic asset, but its value is gradually declining as other sources of energy are developed and as the world begins to shift away from fossil fuels. It spends a lot of money lobbying politicians, which wouldn't be necessary if the alliance were less problematic. Needless to say, the murder of Jamal Khashoggi, atrocities such as the Saudi war in Yemen, and Crown Prince Mohammed bin Salman's erratic approach raise further doubts about the US-Saudi connection. One can raise similar questions about US support for Egypt's military dictatorship, and relations with Turkey are being tested by Ankara's flirtation with Moscow, increasingly undemocratic character, and blithe disregard for US preferences.
With respect to the Middle East, therefore, the United States should adopt a more conditional and businesslike approach to its current partners and its present adversaries. None of its current allies are so valuable or virtuous to deserve unconditional US support, and confining US policy toward Iran to the imposition of even-stricter sanctions just limits US leverage even more. Why should any of its current allies do its bidding when they know it'll back them no matter what? And if the Saudis, Israelis, Egyptians, and others knew the United States was also talking to Iran (something China and Russia do routinely), they might be inclined to do more to keep Washington happy.
Finally, what do these criteria reveal about America's value as an ally? On the one hand, the United States remains the world's single most powerful country, and it can do a lot to help others if it wishes. The United States is also geographically distant from much of the world, so its partners in Eurasia or Africa do not fear it as much as they would if it were right next door. As I wrote way back in 1987, "for the middle level powers of Western Europe and Asia, the United States is the perfect ally. Its aggregate power ensures that its voice will be heard and its actions will be felt. … At the same time, the United States is far enough away so as not to pose a significant threat to [them]."
This situation remains mostly true today, which is why many states still seek US protection against whatever local threats that they perceive. The US political system is also particularly susceptible to foreign penetration and its foreign-policy elite remains committed to what they describe as energetic global leadership, so foreign governments can sometimes persuade Washington to take on distant burdens on their behalf. Trump notwithstanding, the rest of the world is still hoping to get a lot from Uncle Sam.
But on the other hand, that same combination of power and distance also gives the United States considerable latitude to abandon allies once they have ceased to be essential. The United States ultimately left South Vietnam to its fate—just as Trump did with the Syrian Kurds—and is likely to do the same in Afghanistan. Washington has played hardball with key allies on numerous occasions, and as former U.K. Prime Minister Tony Blair could tell you, sometimes it drags them into ill-conceived follies.
The United States' value as an ally is also diminished by its current level of political polarization. No alliance commitment should be thought of as sacrosanct or eternal, but allies have to be able to believe that promises won't be abandoned as soon as the other party captures the White House. Trump's unpredictability and reflexive dishonesty magnify such concerns; at this stage, it is not clear if any senior officials in this administration could make a promise that others would believe. As a result, countries that might want to pitch their lot with the United States have even more reason to hedge their bets.
This problem should not be overstated, however. Because the United States is still so strong and secure, other states will seek its support even when they have certain doubts about its reliability. Indeed, up to a point, their recognition that they need the United States more than it needs them gives Washington considerable leverage in setting the terms of the relationship. That leverage is not absolute, however and US leaders should not blithely assume that others will put up with anything they might do.
The obvious solution to this dilemma is to be more selective in extending commitments in the first place. This is the essence of foreign-policy restraint: The United States should define its interests somewhat more narrowly and then defend those interests more consistently and vigorously. In alliance terms, it means extending commitments only when vital US interests are at stake. Carefully considered commitments will be highly credible, because both allies and adversaries can see for themselves why it is in the US interest to fulfill them. (Pro tip: When it is hard to convince some other country that you really will fight for them, maybe that's telling you something important about their strategic value.)
Among other things, greater selectivity in US alliance pledges would allow Washington to stop fighting in places that don't matter in order to convince others that it will still fight in the places that do. If the United States wants to be seen as a good ally—and it should—it might start by pledging its honor and its citizens' lives only when it will make a direct and significant contribution to US security and prosperity.
Stephen M. Walt is the Robert and Renée Belfer professor of international relations at Harvard University.