Obama still disputes Romney’s claim that Russia top ‘geopolitical foe’

President Obama still is disputing Mitt Romney's campaign trail claim that Russia is America's "number one geopolitical foe," despite the international firestorm created by Vladimir Putin's annexation of Crimea.

The president, speaking at a press conference capping a two-day nuclear security summit at The Hague, was asked about Romney's claim, which the former Republican presidential nominee made during his 2012 race against Obama.

"Russia is a regional power that is threatening some of its immediate neighbors, not out of strength, but out of weakness," Obama said. "Russia's actions are a problem -- they don't pose the number one national security threat to the United States."

Obama said he continues to be more worried about a "nuclear weapon going off in Manhattan."

The comment was the latest in a long-running political tiff that was revived by Russia's actions in Ukraine. Romney was derided by Democrats for calling Russia a top foe in the 2012 race, but the former nominee defended himself in an interview on Sunday, in light of the Ukraine crisis. Romney, speaking with CBS' "Face the Nation," said it is Obama who is being naïve.

"There's no question [about] the president's naiveté with regards to Russia," he said.

Speaking on "Hannity" Tuesday night, Romney reiterated his comments.

"I think the American people understand the facts: Russia is the nation in the world that has opposed us at the U.N. when we wanted to put tougher sanctions on North Korea, opposed us at the U.N. when we wanted to put tougher sanctions on Iran, sides with Assad, in fact, sides with some of the world's worst actors," Romney said. "In terms of who's playing politically against America, of course it's Russia, and of course, the president recognizes it. He may not want to say it."

In case there was any question where Obama now stands on the matter, when a reporter tweeted Tuesday that Obama wouldn't say Romney was right, White House adviser Dan Pfeiffer tweeted back: "[Obama] said he was wrong cuz he was."

Meanwhile, Obama continued to warn Putin not to advance any farther into Ukraine. As for the annexation of Crimea, Obama said it is "not a done deal" in that the international community does not recognize it -- but he acknowledged "there's no expectation that they will be dislodged by force."

Obama said the international community can bring legal and diplomatic arguments to bear, but "it would be dishonest to suggest that there's a simple solution to resolving what has already taken place in Crimea."

Obama heads next to Brussels, after meeting with allies for two days about both Russia and nuclear security. As part of that summit, 35 countries pledged Tuesday to turn international guidelines on nuclear security into national laws, a move aimed at preventing terrorists from getting their hands on nuclear material.

U.S. Energy Secretary Ernest Moniz said the guidelines are now "the closest things we have to international standards for nuclear security."

In a closing communique, all 53 countries that participated in the Nuclear Security Summit in The Hague agreed to keep looking for ways to ensure nuclear material doesn't fall into the hands of terrorists.

But the agreement on adopting guidelines into law was endorsed by just 35. Among other countries that agreed were France, Britain, Canada and Israel; notably absent were Russia, China, India and Pakistan.

The Associated Press contributed to this report.