At a news conference at the Nuclear Security Summit in The Hague, President Obama was asked by Jonathan Karl of ABC News whether Mitt Romney had a point when he called Russia the top "geopolitical foe" of the U.S.

'The World's Always Been Messy': Obama Defends U.S. Response to Putin

He answered that the U.S. has a host of challenges, including Russia threatening its neighbors "out of weakness." Obama believes Vladimir Putin's decision to invade Crimea shows "less influence, not more."

And he ended by saying that he's still more concerned about the threat of a terrorist attack on the U.S., than he is about a threat posed by Russia.

"Russia's actions are a problem. They don't pose the number-one 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," said Obama.

Watch his answer in the video above.