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.