Since 2002, when relations began to seriously deteriorate, the US has been calling for a much tougher stance by the international community against North Korea.
In 2003, it launched the Proliferation Security Initiative (PSI) with the aim of interdicting weapons from North Korea, Iran and other countries of concern. Participating countries were called on to search aircraft and ships suspected of carrying weapons-related material.
In September 2005, Washington imposed financial sanctions on North Korea, accusing it of involvement in the laundering of drug money and counterfeit currency. It froze the assets of eight firms it believed to be linked to the proliferation of weapons of mass destruction, and acted against a bank in Macau accused of helping launder money and of having links with the North Korean leadership.
Following North Korea's July 2006 test launching of seven missiles, the UN Security Council condemned North Korea and called on all members to stop missiles and missile-related technology being transferred to North Korea.
Following North Korea's October 2006 nuclear test, the US pushed for UN condemnation of North Korea, including reference to the UN's Chapter Seven, which could eventually allow for military action.