Vice President Cheney is issuing a stern warning to critics of the war in Iraq and politicians advocating a swift exit from the conflict there: Remember Afghanistan.

Speaking in Manhattan yesterday, Mr. Cheney harked back to America’s involvement in helping the mujahedeen resistance in Afghanistan defeat the invading Soviet army in the 1980s. Once the Soviets evacuated the country, “everybody walked away,” he said. A civil war ensued, the Taliban came to power, and an offer of safe haven was extended to Osama bin Laden, who came to Afghanistan and trained an estimated 20,000 terrorists, some of whom executed the attacks of September 11, 2001, Mr. Cheney said.

“Those who now say we can afford to turn our backs on Iraq are inviting the same kind of outcome that we saw in Afghanistan: a period of chaos and recrimination, a violent power struggle won by a brutal minority, a safe haven for terrorists,” Mr. Cheney said, speaking at a breakfast hosted by a conservative-leaning think tank, the Manhattan Institute.

“The difference is that now we are in the midst of a global war on terror, so failure in Iraq would have even more serious and far-reaching consequences,” he said. The vice president warned that failure in Iraq would embolden Al Qaeda and other terrorist groups by handing them a staging area for further attacks against America. Just as failure has consequences, so does success, Mr. Cheney said. He said a free, democratic Iraq would be a strategic partner for America and send a message to moderates in the region that the West is not indifferent to their future.

“An ideological struggle is under way and in that struggle we can be confident we are doing the right thing. We are confronting the violence, protecting the innocent, liberating the oppressed, and aiding the rise of freedom and democracy as America has done so many times in the past,” he said. He urged people who have insisted that America pull out of Iraq give some thought to what would be left behind.

The vice president also criticized the Democratic leadership of the House of Representatives for allowing the Foreign Intelligence Surveillance Act to expire, a move he said would make tracking enemy plans tougher. He said that leadership is also trying to derail a free trade agreement with Colombia.

Mr. Cheney appeared in good spirits yesterday, recycling a joke he told at the White House Correspondents’ Association dinner last week about people referring to him as Darth Vader. He said yesterday that he had asked his wife if the nickname bothered her, but she told him that it did not.

“It humanizes you,” she told him, he said, prompting laughter from the audience. “So it gives you some perspective on the difficulties I face as vice president,” he added. Mr. Cheney was greeted with robust applause and a standing ovation from the breakfast audience, which one attendee described as generally supportive of the Bush administration, and in particular “the war on terror.” The vice president attended a private fund-raiser for a Rep. Vito Fossella, a Republican, after the speech.

Heaping praise on the Manhattan Institute, Mr. Cheney called the institution one of the most impressive think tanks in the country and said he wished he could bring a “good supply of the common sense and the fresh thinking of the Manhattan Institute” back to Washington.

A senior fellow at the Atlas Economic Research Foundation, Deroy Murdock, praised the speech after Mr. Cheney departed but said he wasn’t sure other New Yorkers would share his opinion. “I imagine that if Vice President Cheney walked into the big hall at Grand Central right now, he might not get quite as warm a reception as he did here,” Mr. Murdock said.