(CNN) -- Sen. John McCain Monday faulted Sen. Barack Obama for downplaying the threat from Iran and again called the Democratic front-runner's judgment "reckless," the latest jabs in a foreign policy fight that could continue to the general election.
Sen. John McCain called Sen. Barack Obama's foreign policy toward Iran "reckless."
Obama's willingness to sit down with the Iranian president demonstrates Obama's lack of understanding of international relations, McCain said during a speech in Chicago, Illinois.
"Such a statement betrays the depth of Senator Obama's inexperience and reckless judgment," McCain said. "Those are very serious deficiencies for an American president to possess."
Obama quickly responded during a speech in Billings, Montana, asking why the presumptive Republican presidential nominee was afraid to talk to Iran and that it was the "Bush-McCain" war policy in Iraq, not diplomacy, that would make Iran stronger.
"Make no mistake, Iran is the single biggest beneficiary of a war in Iraq that should have never been authorized and should have never been waged," the front-runner for the Democratic presidential nomination said. Watch Obama decry the "Bush-McCain" policy »
"Thanks to George Bush's policy, Iran is the greatest threat to the United States and Israel and the Middle East for a generation. John McCain wants to double down on that failed policy."
McCain said Obama did not have an appropriate grasp of the danger Iran poses to the U.S.
"Senator Obama claimed that the threat Iran poses to our security is 'tiny' compared to the threat once posed by the former Soviet Union," McCain said during a speech in Chicago.
"Obviously, Iran isn't a superpower and doesn't possess the military power the Soviet Union had, but that does not mean that the threat posed by Iran is insignificant.
"Should Iran acquire nuclear weapons, that danger would become very dire, indeed," McCain said.
McCain was reacting to a statement Obama made in Pendleton, Oregon, Sunday night while he was defending his view that he would step up diplomatic engagements with Iran -- potentially up to the presidential level -- if he became president. Watch McCain call Obama's judgment "reckless" »
"Iran, Cuba, Venezuela, these countries are tiny compared to the Soviet Union," Obama said. "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.
"We should use that position of strength that we have to be bold enough to go ahead and listen. We might not compromise on any issue, but at least we should find out are there areas of potential common interest, and we can reduce some of the tensions that have caused us so many problems around the world," Obama said.
Obama said he was aware of the "grave" threat Iran poses to the United States, but that it was "common sense" that Iran is less of a threat today to the U.S. than the Soviet Union was during the Cold War.
Obama said just as Presidents John F. Kennedy and Ronald Reagan did during the Cold War, the U.S. should engage diplomatically with its enemies.
"Why shouldn't we have the same courage and confidence to talk to our enemies? That's what strong countries do. That's what strong presidents do," the senator from Illinois said.
"One of the things you have to ask yourself: What are George Bush and John McCain afraid of [in] demanding a country meets all of your conditions before you meet with them?" Obama said.
McCain's attacks on Obama are a continuation of a bitter fight over foreign policy that erupted between the two candidates last week.
In a previous exchange, McCain blasted Obama for what he described as the Democrat's willingness to engage in unconditional talks with Hamas, an Islamic fundamentalist group the U.S. has labeled as a terrorist organization.
Obama denied McCain's claim, saying he would only talk to Hamas if the group renounced its call for Israel's destruction.