Few observers would have expected President Bush’s second inaugural address to draw comparisons with one of the most famous speeches in American history. Yet the parallels to John F. Kennedy’s 1961 inaugural address are unmistakable. That is not necessarily a good thing.

Take Bush’s promise to “stand with … all who live in tyranny and hopelessness.” The sentiment is reminiscent of Kennedy’s saying the U.S. would “pay any price, bear any burden, meet any hardship, support any friend, oppose any foe to assure the survival and the success of liberty.”

But history reveals that Kennedy did not actually expect to pay any price to defend liberty. Less than three months after he had uttered those words, he worried about the fate of the CIA-trained Cuban émigrés who had launched an invasion at the Bay of Pigs to overthrow Fidel Castro. Refusing to “pay any price,” Kennedy altered crucial aspects of the invasion plan for fear that American fingerprints on the operation would arouse the ire of Castro’s patrons in Moscow.

No single decision could have saved the Bay of Pigs invasion. The plan to overthrow Castro’s government with a small force of exiles was bound to fail because it was based on a deeply flawed premise: that there is a wellspring of popular sentiment within undemocratic countries that is simply waiting to be unleashed by American intervention.

The premise is seductive precisely because it is so sensible to people schooled in the benefits of democracy and free-market capitalism. The Cuban émigrés had little difficulty convincing Kennedy & Co. that Castro had a loose grip on power. But the émigrés didn’t have all their facts straight.

If the story of a vocal expatriate community influencing U.S. foreign policy seems familiar, it should. “We are heroes in error,” Ahmed Chalabi of the Iraqi National Congress declared in February 2004. “What was said before is not important.” In other words, the lies he foisted on the American public did not matter to him, because he achieved his goal: the removal of Saddam Hussein from power.

We can now expect similar figures to step forward elsewhere. They will profess to know the deeply felt desires of nearly 70 million Iranians clamoring for U.S. assistance. The Reform Party of Syria regularly flogs the government of Bashar Assad as a suitable target.

In this environment it is nearly impossible to differentiate honest patriots from duplicitous charlatans. By declaring to “democratic reformers” that “America sees you for who you are: the future leaders of your free country,” Bush has placed U.S. foreign policy at the mercy of others who will do anything to draw America into their schemes for power.

Had the President qualified his rhetoric, stressing his hopes for freedom but stopping short of a promise to end tyranny on a global scale, even many of his detractors would have lined up behind him, for even as he rightly celebrated the power of American ideals, he admitted that our considerable power is not unlimited. He might have conceded that our leaders must exercise judgment by identifying and capitalizing on genuine opportunities and avoiding unwise engagements that sap American strength.

Instead, Bush’s incautious words have set the nation on a difficult and dangerous course for the next four years.