WASHINGTON — Vice President Cheney said that the “world is much better off” since the American-led invasion of Iraq and that the Bush administration was right to wage war even though Iraq turned out not to have weapons of mass destruction.

“It was the right thing to do, and if we had to do it over again, we’d do exactly the same thing,” Mr. Cheney said on NBC’s “Meet the Press” program.

Mr. Cheney, in an hour-long interview the day before the fifth anniversary of the September 11, 2001, attacks, said the intelligence at the time supported the primary rationale for the war: that Iraq had weapons of mass destruction.

“It was the intelligence all of us believed,” Mr. Cheney said, repeatedly citing assurances from George Tenet, then the director of the Central Intelligence Agency. Mr. Tenet told the president that the case against Saddam Hussein was a “slam dunk,” Mr. Cheney said. Iraq turned out not to have stockpiles of weapons of mass destruction.

Mr. Cheney defended the Bush administration’s strategy in Iraq and disputed opinion polls that show most Americans think the conflict has created more terrorists, that the war was a mistake, and that Iraq is not the central front on terrorism, as President Bush maintains.

“The people obviously are frustrated because of the difficulty, because of the cost and the casualties,” Mr. Cheney said. “You cannot look at Iraq in isolation.You have to look at it within the context of the broader global war on terror.”

Any retreat by America in Iraq would indicate to the terrorists that the “U.S. has lost its will” in the war against terrorism and would damage American credibility with allies in the region, Mr. Cheney said.

The vice president defended his statements before the war that Americans would be greeted as liberators and that he did not expect the war to be lengthy and cost many lives.

“That’s true within the context of the battle against the Saddam Hussein regime and his forces,” Mr. Cheney said. “That went very quickly.” The subsequent insurgency has been “long and costly and bloody,” he said.

Two reports released Friday by the Senate Intelligence Committee said Bush administration claims justifying the war against Iraq were based on intelligence that was fragmented, conflicting, and at times unreliable.

Administration statements that Saddam Hussein was allied with Al Qaeda leader Osama bin Laden and was helping the terrorist group obtain chemical and biological weapons proved wrong and misleading and were not based on solid intelligence in its possession, the declassified Senate reports said.

Secretary of State Rice also defended the Bush administration and its strategy in Iraq on “Fox News Sunday,” one of three shows on which she appeared.

“Iraq is going through very difficult times,” Ms. Rice said. “But if you have a broad view of what it will take to defeat extremism, meaning that there will have to be a different kind of environment in the Middle East, it’s hard to imagine that different kind of environment with Saddam Hussein in power and Iraq at the center of a nexus between terrorism and conflict.”

The chairman of a commission tasked with investigating the September 11 attacks, Thomas Kean, said the Iraq war has bred terrorists.