WASHINGTON — Vice President Dick Cheney said yesterday that Iran is a top threat to world peace and Middle East stability, accusing Tehran of sponsoring terrorism against Americans and building a "fairly robust new nuclear program."

In an interview aired on MSNBC's "Imus in the Morning" show a few hours before President Bush's inaugural address, Cheney warned that Israel "might well decide to act first" militarily to eliminate Iran's nuclear capabilities if the United States and its allies fail to resolve the standoff with Tehran diplomatically.

"Given the fact that Iran has a stated policy that their objective is the destruction of Israel, the Israelis might well decide to act first, and let the rest of the world worry about cleaning up the diplomatic mess afterwards," Cheney said. In 1981, Israel sent warplanes to destroy Iraq's nuclear reactor.

"We don't want a war in the Middle East, if we can avoid it," he said. Iran denies that its nuclear facilities are used for producing nuclear weapons; the Bush administration disagrees.

The Pentagon has denied a report in this week's New Yorker magazine that the United States is conducting secret reconnaissance missions in Iran to identify potential nuclear targets.

In the interview with Don Imus, the vice president made a rare admission, saying he had miscalculated how quickly Iraqis would be able to recover from Saddam Hussein's government and begin running their country.

"I think the hundreds of thousands of people who were slaughtered at the time, including anybody who had the gumption to stand up and challenge him, made the situation tougher than I would have thought," he said. "I would chalk that one up as a miscalculation, where I thought things would have recovered more quickly."