The NATO summit starts Sunday in Chicago and will be the largest gathering ever held by the alliance. This is fitting given NATO’s desire to act around the globe. While U.S. officials say no decisions on further expanding membership will be made at the meeting, they explain that the door remains open. Adding additional security commitments in this way would be a mistake. 

The United States has always been and will continue to be the guarantor of NATO’s military promises. In reality, NATO could not pay its bills without the United States, much less conduct serious military operations. American alliance policy has become a form of foreign aid. Nowhere is that more true than in Europe.

America’s alliances once had a serious purpose: to increase U.S. security. NATO joined the United States and Western Europe to prevent the Soviet Union from dominating Eurasia. The alliance lost its raison d’être in 1989 when the Berlin Wall fell. Communist regimes throughout Eastern Europe had toppled. The Warsaw Pact soon dissolved. Ultimately the Soviet Union collapsed.

Yet 23 years later NATO labors on, attempting to remake failed societies and anoint winners in civil wars. There’s no big threat left: Russia isn’t going to revive the Red Army and conquer the European continent. Moscow was barely capable of beating up on hapless Georgia.

Moreover, the Euro zone crisis threatens to turn NATO’s military capabilities into a farce. Virtually every European state is cutting back on its military, even France and Great Britain, which traditionally had the most serious—and most deployable—forces. NATO always looked like North America and The Others. Today the only power prepared to battle even a decrepit North African dictatorship is America.

Yet like the Borg of Star Trek fame, the alliance wants to ever-expand, absorbing every country in its path. Bosnia—an artificial nation who military was cobbled together from three warring factions—hopes to join. So, too, Macedonia, which remains at odds with Greece over its very name. Georgia, which triggered a war with Russia in apparent expectation of receiving U.S. support, wants in. Montenegro, which has no military of note, is also interested.

There is even talk of adding Kosovo, another artificial country in which the majority ethnically cleansed national and religious minorities while under allied occupation. Serbia, bombed by NATO in 1999 and still resisting Kosovo’s secession, is on the long list. As is Ukraine, a country with a large Russophile population and a government that acts more Russian than Western.

Adding these countries would greatly expand America’s liabilities while adding minimal capabilities. The United States would have to further subsidize the new members to bring their militaries up to Western standards while making their disputes and controversies into America’s disputes and controversies. Worst would be expanding the alliance up to Russia’s southern border, giving further evidence to Moscow of a plan of encirclement. As Henry Kissinger once said, even paranoids have enemies. Indeed, Washington would not react well if the Warsaw Pact had included Mexico and Canada.

The United States cannot afford to take on more allies and effectively underwrite their security. It is not worth protecting Georgia at the risk of confronting Russia, for instance. Moreover, now is the time to end this foreign aid to wealthy European countries. The Europeans have a GDP ten times as large as that of Russia. Europe’s population is three times as big. The Europeans should defend themselves. If they want to expand their alliance all around Russia, let them. But the U.S. government, bankrupt in all but name, should finally focus on defending Americans, not most everyone else in the world.