There’s a lot to be said for an alliance. It bolsters not only the defense of each nation that enters into the agreement, but it also helps to further develop a friendly sense of cooperation, as the terms of mutual defense often lead to an air of cooperation in economic and social realms as well. Over the years, America’s role as a diplomatic leader and military superpower has led to the development of a number of treaties and alliances, each aimed at helping to improve relations with global partners and offering a stabilizing presence in the region.

Of course, America maintains the largest and most capable military on the planet, so one might ask what purpose a long list of alliances could actually serve, but that speaks to a common misconception about American military prowess: the United States may indeed have the most powerful military force on the planet, but that force can’t be everywhere at once. American stands the chance of legitimately losing a number of regional conflicts, were they to break out, simply because the breadth of its force are all entangled in other endeavors scattered across the globe. Put simplistically; it just doesn’t matter that America has ten more aircraft carrier strike groups in its arsenal if there’s only one that can make it to the fight without leaving American interests elsewhere undefended.

But then, there’s something to be said for the stabilizing effect of the alliance itself. While the obvious purpose of entering into a mutual defense agreement with another nation is garnering their military support in the event of a conflict, that agreement serves as a powerful deterrent against those very conflicts themselves. Montenegro, as has been in the headlines recently, is a tiny nation with a total population of only about 1.3 million. Russia has nearly that many people serving on active duty in their military alone. However, add the collective might of the NATO alliance to Montenegro’s defense, as they did when entering into the alliance more than a year ago, and suddenly the tiny nation no longer as easily defeated. While there’s no guarantee that war will not come to Montenegro, its inclusion in the NATO alliance will likely prevent it for some time to come.

The total number of nations America would go to war to defend is subject to some debate, in part due to the diplomatic language employed in international agreements, and in part because geopolitical relationships are constantly evolving. By the estimate of Michael Beckley, an assistant professor in the Department of Political Science at Tufts University, the United States is obligated to go to war alongside no fewer than 69 nations, placing at least one-quarter of the entire planet’s population under the protection of American military might. However, the U.S. State Department offers a slightly smaller number at 54 — though that figure doesn’t seem to have been updated since Montenegro’s inclusion in the NATO alliance, bringing the total figure up to 55.