The foreign policy fight between John McCain and Barack Obama flared up again Monday when the candidates jabbed one another over over how to address the threat posed by Iran.

While the two have been feuding since President Bush last week told the Israeli Knesset, or parliament, that a policy of appeasement is a "foolish delusion," the heated rhetoric rose a notch after Obama said Sunday night that Iran is not an equivalent threat to the Soviet Union.

"Iran, Cuba, Venezuela -- these countries are tiny compared to the Soviet Union. They don't pose a serious threat to us the way the Soviet Union posed a threat to us. And yet we were willing to talk to the Soviet Union at the time when they were saying we're going to wipe you off the planet," Obama told voters in Pendleton, Ore.

"You know, Iran, they spend one-one hundredth of what we spend on the military. If Iran ever tried to pose a serious threat to us, they wouldn't stand a chance. And we should use that position of strength that we have to be bold enough to go ahead and listen," he said.

Obama has called for unconditional direct talks between the U.S. and Iran, saying the U.S. would be negotiating from a position of strength. He has since modified that call, saying that mid-level meetings would have to set an agenda and criteria before direct talks could be conducted.

Speaking to the National Restaurant Association on Monday, McCain said Obama doesn't understand that a summit meeting with a U.S. president is the ultimate form of diplomacy, and not one to be squandered on a nation that is unrepentant about its pursuit of nuclear weapons, its desire to blow Israel off the map and its frequent attacks on U.S. soldiers in Iraq.

"Senator Obama has declared, and repeatedly reaffirmed his intention to meet the president of Iran without any preconditions, likening it to meetings between former American presidents and the leaders of the Soviet Union. Such a statement betrays the depth of Senator Obama’'s inexperience and reckless judgment. Those are very serious deficiencies for an American president to possess," McCain said.

"It is likely such a meeting would not only fail to persuade him to abandon Iran’s nuclear ambitions; its support of terrorists and commitment to Israel’s extinction, it could very well convince him that those policies are succeeding in strengthening his hold on power, and embolden him to continue his very dangerous behavior. The next president ought to understand such basic realities of international relations," he continued.

Responding almost immediately, Obama, who was in Billings, Mont., on Monday, said he understands that Iran is a grave threat, but it's important to engage enemies as well as friends.

"That is what diplomacy is all about," he said, adding that Iran's strength has grown primarily "because of the Bush-McCain policy of fighting an endless war in Iraq."

Iran, Obama said, is the "single biggest beneficiary of a war that should never have been authorized and never have been waged."