A group of nations ostensibly concerned about a common threat agree to defend one another in the event of an attack. "All for one and one for all," as the Three Musketeers said.

But like many things, the principle, even if sincerely invoked, is more problematic than the first glance indicates. This is particularly true with governments, and in no area more so than foreign policy and armed forces. Schoolyard analogies involving bullies do not hold.

NATO was established soon after World War II ostensibly to keep the Soviet Union from overrunning Western Europe. The Red Army was present in Eastern and Central Europe, including eastern Germany, having driven back the Wehrmacht in the Allied defeat of Nazi Germany. It is by no means clear that Soviet dictator Josef Stalin aspired to have his armed forces conquer Western Europe, and his doctrine of "socialism in one country," which suggests a conservative foreign policy, hardly supports a militarily aggressive posture toward the West. For one thing, the Soviet Union was exhausted from the savage war — it lost well over 20 million military personnel and civilians — and was hardly in a position to begin a new one against the Americans.

While many American politicians, fearing a return of the prewar public sentiment against foreign intervention, spoke of a Soviet threat, not all agreed. The influential Republican senator Robert A. Taft of Ohio, whom I will discuss below, questioned the consensus and thus the official premise of the Cold War.

On April 4, 1949, 12 countries — the United States, Canada, Great Britain, France, Belgium, the Netherlands, Luxembourg, Portugal, Italy, Norway, Denmark, and Iceland — signed the treaty that created NATO. (The Warsaw Pact, the Soviet Union's counter-alliance with the Eastern European countries it occupied, would not be founded for another six years.) Since 1998, 18 more countries have joined NATO, for a total of 30, including former Warsaw Pact members and the former Soviet Baltic republics that border Russia — with the predicted disastrous consequences. (Austria is not a member, having agreed to neutrality in 1955, in return for the Soviet withdrawal. West Germany became a member in 1955, and then a reunified Germany became a member in 1990 as the Soviet Union and Warsaw Pact were being dismantled.)