MOSCOW, July 6 (RIA Novosti) - The leaders of Russia and the United States discussed the nuclear programs of North Korea and Iran during their meeting in Moscow on Monday, U.S. President Barack Obama said.

"As we keep our commitments, so we must insure that other nations keep theirs. To that end we had constructive discussions on North Korea and Iran," Obama said at a joint news conference in Moscow.

He thanked Russia for its support of the UN Security Council resolution, which toughened existing sanctions against North Korea and imposed new ones following Pyongyang's May 25 nuclear test.

"North Korea has abandoned its own commitments and violated international law," the U.S. leader said. "That's why I'm pleased that Russia joined us in passing UN Security Council resolution that calls for strong steps to block North Korea's nuclear and ballistic missile programs."

Obama added that Iran's failure to comply with its international obligations also posed a serious challenge.

"It raises the prospect of a nuclear arms race in the Middle East, which will endanger global security, while Iran's ballistic missile program could also pose a threat to a broader region," he said.

President Dmitry Medvedev said Russia and the United States should cooperate closely on nuclear non-proliferation issues in these regions.

"It is of common knowledge that the situation on the planet depends on the situation in the Korean Peninsula, in the Middle East," the Russian leader said.

He added that the problem was a mutual responsibility for the two countries and should be dealt with "as thoroughly as possible."