WASHINGTON - President Barack Obama said his focus on nuclear disarmament had strengthened U.S. diplomacy in dealing with North Korea and Iran, and he warned Tehran faced growing consequences over its nuclear program.

In his State of the Union address to Congress on Wednesday, Obama touched on some of the thorniest foreign policy issues he has faced in the past year, including his effort to develop a new approach toward Iran and North Korea as they expand their nuclear programs.

Obama, whose new initiative to curb nuclear weapons helped earn him the Nobel Peace Prize, said he was working with Russia to complete a major nuclear arms reduction treaty.

The two sides failed to reach an agreement on a replacement for the strategic arms reduction treaty, START, before it expired in early December. But they agreed to extend the protections of the treaty as they continue negotiations, which are due to resume on Monday in Geneva.

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 told Congress.

And at April's Nuclear Security Summit, we will bring 44 nations together behind a clear goal: securing all vulnerable nuclear materials around the world in four years so that they never fall into the hands of terrorists.

INTERNATIONAL APPROACH

Obama said his focus on an international approach to reducing nuclear arms and preventing proliferation had strengthened our hand in dealing with those nations that insist on violating international agreements in pursuit of these weapons.

He referred specifically to North Korea and Iran, which says its uranium enrichment program is aimed at developing nuclear energy and not atomic weapons.

The focus on nuclear arms control 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.

North Korea detonated an underground nuclear device early in the Obama administration, its second test since 2006. And it test-fired short-range missiles on several occasions, rattling its neighbors.

Obama took office calling for a new relationship with Iran, including a more direct dialogue. The two countries have not had diplomatic relations since 1980, when Washington broke off ties during the hostage crisis at the U.S. Embassy in Tehran.

Iran has resisted initiatives by the United States and other major powers aimed at curbing its nuclear enrichment activity and building international confidence that Tehran is not trying to develop atomic weapons.

Tehran has so far rejected a proposal that would allow it to ship its partially enriched uranium abroad to be further enriched for use in a research reactor. The idea was proposed by a negotiating group that includes the United States, Russia, China, Britain, France and Germany.

(Editing by Chris Wilson)

Russia Barack obama Nuclear weapons Nuclear Security Summit