US President Barack Obama on Wednesday warned Iran and North Korea of growing isolation if they pursue nuclear weapons as he highlighted his vision of a world free from the destructive arms.

Obama, who has faced growing criticism from his base for stepping up the war in Afghanistan, pointed to his anti-nuclear efforts in an annual address to Congress mostly devoted to how to revive the troubled US economy.

"Even as we prosecute two wars, we are also confronting perhaps the greatest danger to the American people -- the threat of nuclear weapons," Obama said in his State of the Union address.

Obama said that his diplomacy against nuclear arms has "strengthened our hand in dealing with those nations that insist on violating international agreements in pursuit of these weapons."

"That is why North Korea now faces increased isolation, and stronger sanctions -- sanctions that are being vigorously enforced," Obama said.

"That is why the international community is more united, and the Islamic Republic of Iran is more isolated," he said.

"And as Iran's leaders continue to ignore their obligations, there should be no doubt: they, too, will face growing consequences."

Obama in a speech last year in Prague passionately called for the United States -- the only nation to have used nuclear weapons in war -- to set the path for an end to the destructive arms.

He pointed to progress in efforts to reach a new disarmament treaty with Russia. Talks resume Monday in Geneva on a successor to the Strategic Arms Reduction Treaty (START) which was first agreed in 1991 and expired last month.

"To reduce our stockpiles and launchers, while ensuring our deterrent, the United States and Russia are completing negotiations on the farthest-reaching arms control treaty in nearly two decades," Obama said.

He spoke as North Korea conducted a second day of live-fire artillery exercises near its tense sea border with South Korea, ignoring US requests to halt the "provocative" drill.

The United States led an international drive to intensify sanctions on North Korea last year after the communist state conducted its second-ever test of a nuclear bomb.

Obama has reached out to Iran, offering dialogue to end three decades of animosity since the 1979 Islamic revolution overthrew the pro-Western shah.

But the administration has been increasingly frustrated with Iran's response and suspects that the regime is trying to build nuclear weapons in defiance of international appeals.