But Mr. Cheney reserved his harshest language for Iran. Calling it “the world’s most active state sponsor of terrorism,” he said, “our country, and the entire international community, cannot stand by as a terror-supporting state fulfills its most aggressive ambitions.”

That language is not radically different from what Mr. Cheney has used in the past. But people at the conference said that, placed in the context of Mr. Bush’s remarks, it represented a significant step toward increasing pressure on Iran. The speech seemed to lay the groundwork for the threat of military action — either because the administration actually intends to use force or because it wants to use the threat of force to prod Europe into action.

“This week we heard a significant ratcheting up of the rhetoric,” said Dennis Ross, who served as a Middle East envoy for President Clinton and the first President Bush and is now a scholar at the Washington Institute. Repeating Mr. Cheney’s remark about serious consequences, he said those were “strong words” with “serious implications.”

Mr. Bush has repeatedly said the administration would not “tolerate” a nuclear-armed Iran. But during a news conference on Wednesday, the president went further, saying of Iran: “If you’re interested in avoiding World War III, it seems like you ought to be interested in preventing them from having the knowledge necessary to make a nuclear weapon.”

That distinction — having the knowledge to make a nuclear weapon, as opposed to actually having a weapon — is one the administration has not made in the past. David Makovsky, a senior fellow at the Washington Institute who moderated a panel discussion before and after Mr. Cheney’s speech, said the vice president also seemed to draw a new red line when, instead of saying it is “not acceptable” for Iran to have a nuclear weapon, he said the world “will not allow” it.