NASHVILLE, Tennessee -- The U.S. presidential candidates assailed Russia in their latest debate, with Democrat Barack Obama saying Moscow had engaged in "evil" behavior and Republican John McCain saying it was "maybe" an evil empire.

In Tuesday's debate, the two candidates were asked the barbed question, "Do you think that Russia under Vladimir Putin is an evil empire?" and were asked to reply "yes" or "no."

Both stopped short of saying "yes" or "no" but made plain that they have problems with Russia.

"I think they've engaged in an evil behavior, and I think that it is important that we understand they're not the old Soviet Union, but they still have nationalist impulses that I think are very dangerous," Obama said.

"Maybe," McCain answered, adding, "If I say yes, then that means that we're reigniting the old Cold War. If I say no, it ignores their behavior."

In reply to an earlier question in the debate, McCain and Obama denounced Russia's military push in August into Georgia, the first such offensive outside its territory since the 1991 collapse of the Soviet Union. Moscow's action followed a crackdown by Georgia on rebels of the breakaway region of South Ossetia.

"I think we can deal with [the Russians], but they've got to understand that they're facing a very firm and determined United States of America that will defend our interests and that of other countries in the world," McCain said.

Former U.S. President Ronald Reagan used the phrase "evil empire" for the first time in a March 8, 1983, speech to the National Association of Evangelicals in Orlando, Florida.