United Nations ? The U.N. Security Council imposed punishing new sanctions on North Korea Friday, toughening an arms embargo and authorizing ship searches on the high seas in an attempt to thwart the reclusive nation’s nuclear and ballistic missile programs.

The unanimous support for the resolution reflected international disapproval for recent actions by North Korea, which defied the council by conducting a second nuclear test on May 25 and heightened global tensions with recent missile launches that raised the specter of a renegade nuclear state.

North Korea has repeatedly warned that it would view new sanctions as a declaration of war, but it boycotted Friday’s vote — in sharp contrast to the October 2006 Security Council meeting where sanctions were imposed after the country’s first nuclear test. Then, the North Korean ambassador immediately rejected the resolution, accused council members of “gangster-like” action and walked out of the council chamber.

U.S. Ambassador Susan Rice, who shepherded the resolution through two weeks of complex and sometimes difficult negotiations, told reporters in Washington that the administration was “very pleased” with the council’s “unprecedented” and “innovative” action.

She cautioned that North Korea could react to the resolution with “further provocation.”

“There’s reason to believe they may respond in an irresponsible fashion to this,” she said.

North Korea said Monday in its main newspaper that it would respond to any new sanctions with “corresponding self-defense measures.” On Tuesday, the North said it would use nuclear weapons in a “merciless offensive” if provoked.

The resolution seeks to deprive North Korea of financing and material for its weapons program and bans the communist country’s lucrative arms exports, especially missiles. It does not ban normal trade, but does call on international financial institutions to halt grants, aid or loans to the North except for humanitarian, development and denuclearization programs.