Am I my brother’s keeper? If you’re the United States, the answer is yes, and you have a big family.

The United States is obligated by treaty or otherwise to come to the defense of 67 other countries if they’re attacked, according to The Myth of Entangling Alliances (pdf) by Michael Beckley. Those obligations include obvious ones such as to Israel, with which the U.S. has no formal treaty, but has made many pledges of support. But it also includes Cuba, which only last week came off the list of state sponsors of terrorism. As a member of the Organization of American States, Cuba is a potential beneficiary of U.S. military support if it’s attacked.

Not that having a treaty necessarily means the United States will spring into action if a signatory nation is attacked. There is a defense treaty with Pakistan, for instance, which has gone to war with India several times. In none of those incidents have U.S. troops been sent in. Nor did Americans come to the aid of the French when they asked for help during the 1954 battle of Dien Bien Phu in Vietnam.

The idea that the United States is the world’s older brother, ready to take care of any bullies that show up on a street corner, is relatively recent. For the first 165 years of its existence, the United States had one such treaty, signed with France during the Revolutionary War, according to Beckley. After World War II though, organizations such as the North Atlantic Treaty Organization (NATO) formed in the early days of the Cold War obligated the U.S. to jump in if a member nation were to be attacked. The State Department, by the way, counts only 55 nations that Americans are obligated to defend.

Beckley concludes that it isn’t alliances that cause the United States to go to war, but the intentions of its leaders. “The empirical record shows that the risk of entanglement is real but manageable and that, for better or worse, U.S. security policy lies firmly in the hands of U.S. leaders and is shaped primarily by those leaders’ perceptions of the nation’s core interests,” he wrote. “When the United States has overreached militarily, the main cause has not been entangling alliances but rather what Richard Betts calls ‘self-entrapment’—the tendency of U.S. leaders to define national interests expansively, to exaggerate the magnitude of foreign threats, and to underestimate the costs of military intervention.”

-Steve Straehley

To Learn More:

The U.S. Is Bound by Treaties to Defend a Quarter of Humanity (by Adam Taylor, Washington Post)

The Myth of Entangling Alliances (pdf) (by Michael Beckley, International Security)

U.S. Collective Defense Arrangements (Department of State)