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.

These nations are broken down into seven “collective defense agreements” signed and maintained by the United States, and it includes some countries you might be surprised to find in any form of alliance with the U.S. — like Cuba.

What follows is a list of these agreements and the signatory member nations of each, as provided by the State Department. According to official U.S. policy, an attack on any of these nations could be considered an attack on the United States itself:

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The NATO Alliance

A treaty signed April 4, 1949, by which the Parties agree that an armed attack against one or more of them in Europe or North America shall be considered an attack against them all; and each of them will assist the attacked by taking forthwith, individually and in concert with the other Parties, such action as it deems necessary, including the use of armed force.

Nations allied to the United States through this treaty: Albania, Belgium, Bulgaria, Canada, Croatia, Czech Republic, Denmark, Estonia, France, Germany, Greece, Hungary, Iceland, Italy, Latvia, Lithuania, Luxembourg, Montenegro, Netherlands, Norway, Poland, Portugal, Romania, Slovak Republic, Slovenia, Spain, Turkey, United Kingdom

U.S. Alliance with Australia and New Zealand

A Treaty signed September 1, 1951, whereby each of the parties recognizes that an armed attack in the Pacific Area on any of the Parties would be dangerous to its own peace and safety and declares that it would act to meet the common danger in accordance with its constitutional processes.

Nations allied to the United States through this treaty: Australia, New Zealand

Philippine Treaty (Bilateral)

A treaty signed August 30, 1951, by which the parties recognize that an armed attack in the Pacific Area on either of the Parties would be dangerous to its own peace and safety and each party agrees that it will act to meet the common dangers in accordance with its constitutional processes.

Nations allied to the United States through this treaty: Philippines

Southeast Asia Treaty

A treaty signed September 8, 1954, whereby each party recognizes that aggression by means of armed attack in the treaty area against any of the Parties would endanger its own peace and safety and each will in that event act to meet the common danger in accordance with its constitutional processes.

Nations allied to the United States through this treaty: Australia, France, New Zealand, Philippines, Thailand, and the United Kingdom

Japanese Treaty (Bilateral)

A treaty signed January 19, 1960, whereby each party recognizes that an armed attack against either Party in the territories under the administration of Japan would be dangerous to its own peace and safety and declares that it would act to meet the common danger in accordance with its constitutional provisions and processes. The treaty replaced the security treaty signed September 8, 1951.

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Nations allied to the United States through this treaty: Japan

Treaty with the Republic of Korea (Bilateral)

A treaty signed October 1, 1953, whereby each party recognizes that an armed attack in the Pacific area on either of the Parties would be dangerous to its own peace and safety and that each Party would act to meet the common danger in accordance with its constitutional processes.

Nations allied to the United States through this treaty: South Korea

The Rio Treaty

A treaty signed September 2, 1947, which provides that an armed attack against any American State shall be considered as an attack against all the American States and each one undertakes to assist in meeting the attack.

Nations allied to the United States through this treaty: Argentina, Bahamas, Bolivia, Brazil, Chile, Colombia, Costa Rica, Cuba, Dominican Republic, Ecuador, El Salvador, Guatemala, Haiti, Honduras, Nicaragua, Panama, Paraguay, Peru, Trinidad & Tobago, Uruguay, Venezuela

Featured image: Gunners from the 2nd Cavalry Regiment carry out a mission on the M777 howitzer. Exercise Dynamic Front 18 includes approximately 3,700 participants from 26 nations at the Grafenwoehr Training Area, Germany, Feb. 23 to March 10, 2018. Dynamic Front is an annual U.S. Army Europe exercise focused on the interoperability of U.S. Army, joint service and allied nation artillery and fire support in a multinational environment, from theater-level headquarters identifying targets to gun crews pulling lanyards in the field. | U.S. Army photo by Chief Warrant Officer Two Tom Robinson