Because the geostrategic arguments for the U.S. alliance system are tenuous, they are seldom made. Instead, we are treated to tales of Russian and Chinese threats to the "rule based international order." This "order" is simply the military alliance and trading system that the United States built to wage the Cold War, and which the foreign-policy establishment assumed upon the end of that great struggle would naturally grow to encompass all the other countries of the world. Russia and China want to have exchange relationships with this order; they don't want to be in it; and they don't like its relentless expansion to their borders, which is how Russia in particular views NATO and EU enlargement. Is this "order" nice to have? Sure, though the net benefits are difficult to measure and are usually overstated. Is this order so essential to U.S. national security that the United States should be disproportionately contributing to its defense, to include assuming severe nuclear risks? On the whole, I do not think so, but this is a fit subject for a real debate, which we will not get this political season.

We can be reasonably certain, whether Donald Trump or Hillary Clinton wins the Presidency, that the United States will remain committed to its alliance system. Given Mr. Trump's clear awareness of alliance "cheap riding," why venture such a prediction? He will need to staff his administration. The Republican foreign-policy establishment disagrees with him, and he will be forced to use their services because there isn't anyone else he can use. The ideologues who brought the Baltics into NATO, and brought the United States into Iraq, will not cooperate in the reversal of their revolutionary projects. The ensuing Republican internal guerrilla warfare would be fun to watch, but I suspect the guerrillas would win. Mrs. Clinton's views, on the other hand, are well established. She is a booster of the present system and her policies will reflect it, as did the security vignettes of the Democratic Party’s convention.

Both candidates will nevertheless find themselves facing significant pressures to reform the workings of the U.S. alliance system. The simple fact is that however fast or slowly China is growing, it is growing. No matter how fast or slowly Russia is declining, it is no longer flat on its back and the Russians remain competent at building military power. In their home regions, Al Qaeda, ISIL, the Taliban or whatever nihilistic organizations succeed them have learned how to fight the Americans, and they take the long view. The liberation of Mosul will likely not mark the end of ISIL. The costs of the U.S. alliance system, and the strategy of "liberal hegemony" in which it is embedded, are destined to grow. Meanwhile, there is so far no sign that the gridlock in U.S. domestic politics is going to end: budget compromises will likely constrain the growth of the U.S. defense budget, even as U.S. defense costs for any given size of military continue to grow relentlessly, as they have for decades. Given these likely pressures, Trump or Clinton will be forced to revisit real defense burden sharing. It is very hard to get the zllies to hold up their end because the United States promises so much. And U.S. leaders do not like the political optics of public spats with allies. Enormous diplomatic determination, and willingness not only to tolerate but to precipitate tense intra-alliance relations, will be necessary to achieve real burden sharing. If the foreign-policy establishment across the two parties wishes to keep the grand strategy they have, even they will need to figure out a real, and not a rhetorical strategy to induce the allies to do more.

This is the fourth in a series of essays on the future of American primacy. You can read the previous essay, “Is Primacy Overrated?” by Robert D. Kaplan, here.

Barry R. Posen is Ford International Professor of Political Science, MIT and Director of their Security Studies Program. He is the author of Restraint- A New Foundation for U.S. Grand Strategy.

Image: “Photo shows Soldiers from Germany participating in the Strong Europe Tank Challenge (SETC) May 08, 2016 at Grafenwoehr Training Area, Germany. The SETC is co-hosted by U.S. Army Europe and the German Bundeswehr May 10-13, 2016. The competition is designed to foster military partnership while promoting NATO interoperability. Seven platoons from six NATO nations are competing in SETC - the first multinational tank challenge at Grafenwoehr in 25 years. For more photos, videos and stories from the Strong Europe Tank Challenge, go to http://www.eur.army.mil/tankchallenge/ (U.S. Army photo by Visual Information Specialist Markus Rauchenberger/released)”