Camp David is widely known. Not so well known is another foreign-policy achievement of the Carter administration, one that has a direct link to the terrorist attacks on the United States and the ensuing “war on terrorism.”

Not long after Camp David, the administration took a fateful step, the consequences of which will plague us for many years to come. It gives a bitter irony to Mr. Carter’s Peace Prize.

On July 3, 1979, Mr. Carter signed a directive authorizing secret aid to Islamic opponents of the pro-Soviet regime in Afghanistan. The turmoil that followed prompted the Soviet government to send its army across the border. The American people have been led to believe that the U.S. government got involved in Afghanistan only after the Soviet Union invaded that country. That is not true. Mr. Carter’s directive came five months before the Soviet invasion. What’s more, it was intended to provoke it.

How do we know that? Mr. Carter’s national security advisor, Zbigniew Brzezinski revealed it in 1998. In an interview with the French publication Le Nouvel Observateur, Brzezinski set out his thinking at the time. “And that very day [that Carter signed the order], I wrote a note to the president in which I explained to him that in my opinion this aid was going to induce a Soviet military intervention.... We didn’t push the Russians to intervene, but we knowingly increased the probability that they would.”

Asked if he regretted the decision, Brzezinski replied, “Regret what? That secret operation was an excellent idea. It had the effect of drawing the Russians into the Afghan trap and you want me to regret it? The day that the Soviets officially crossed the border, I wrote to President Carter: We now have the opportunity of giving to the USSR its Vietnam war.”

The U.S.-aided Afghan forces fighting the Soviets — the mujahideen — became the Taliban. Their radical Arab associates became al-Qaeda, led by Osama bin Laden.

When asked if he regretted helping “future terrorists,” Brzezinski said, “What is most important to the history of the world? The Taliban or the collapse of the Soviet empire? Some stirred-up Moslems or the liberation of Central Europe and the end of the cold war?”

When reminded — this was 1998 remember — that the “stirred-up Moslems” were regarded as a “world menace,” he said, “Nonsense!” and denied there was any such thing as “global Islam.”

The Arab Islamic radicals whom the Carter administration indirectly helped turn into a formidable power didn’t just want to rid Afghanistan of the Russians. Later they would also decide to rid the Muslim world of the Americans, especially when the United States in 1990 stationed troops in Saudi Arabia, bin Laden’s native country.

Jimmy Carter’s government thus helped start a process that led to the training, arming, and financing of America’s own future potential enemies. Succeeding administrations then provoked them by engaging in what looked like imperialism to the people on the receiving end of the policies. That’s what the CIA calls “blowback.”

The now-celebrated man of peace plotted to ignite an extended war, complete with the decade of death and devastation he had every reason to expect. His motive was to bring down the Soviet Union. Of course, he never expected his policy to help set in motion the force that would murder 3,000 innocent American civilians more than 20 years later. But that’s how the Law of Unintended Consequences works in foreign affairs.

In his Nobel address, Mr. Carter said, “War may sometimes be a necessary evil. But no matter how necessary, it is always an evil, never a good. We will not learn to live together in peace by killing each other’s children.”

Too bad he didn’t think of that when he was in office. A lot of lives might have been saved in New York City.

Sheldon Richman is senior fellow at The Future of Freedom Foundation in Fairfax, Va., and editor of Ideas on Liberty magazine and author of “‘Ancient History’: U.S. Conduct in the Middle East since World War II and the Folly of Intervention.”.