THE HAGUE, Netherlands (AP) — President Barack Obama says he's more concerned about the prospect of a nuclear weapon exploding in New York City than Russia's recent actions and called President Vladimir Putin's country "a regional power."

During a news conference Tuesday, a reporter asked Obama whether his opponent in the last presidential campaign, Mitt Romney, had a point when he described Russia as America's top geopolitical foe. At the time, Obama criticized that characterization. Since then, Russia has annexed Crimea.

"With respect to Mr. Romney's assertion that Russia is our No. 1 geopolitical foe, the truth of the matter is that America has got a whole lot of challenges. Russia is a regional power that is threatening some of its immediate neighbors not out of strength, but out of weakness," Obama said at the conclusion of a nuclear security summit.

He later said Russia's actions were a problem but didn't pose the top national security threat to the United States.

"I continue to be much more concerned when it comes to our security with the prospect of a nuclear weapon going off in Manhattan," he said, "which is part of the reason why the United States, showing its continued international leadership, has organized a forum over the last several years that's been able to help eliminate that threat in a consistent way."

While calling Russia the nation's top geopolitical foe during the campaign for the White House, Romney said Iran was the top security threat to the U.S. because of its nuclear ambitions.