He told a Senate hearing that North Korea's claim to have nuclear weapons "is probably true" and "has threatened to proliferate these weapons abroad."

Like Iran, which is poised to be dragged to the UN Security Council over suspected atomic weapons work, North Korea "threatens international security and is located in a historically volatile region," Negroponte said.

"Its aggressive deployment posture threatens our allies in South Korea and US troops on the (Korean) peninsula," he said.

Some 32,500 US soldiers are stationed in South Korea to help Washington's ally face up to North Korea's 1.2-million-strong army under a mutual defense treaty dating back to the 1950-1953 Korean War.

The United States is engaged with China, Russia, South Korea and Japan in six-party talks with North Korea to end the Stalinist state's nuclear weapons drive but the negotiations have stalled since November.

Pyongyang has said it will not return to the talks unless Washington withdraws financial sanctions it has imposed for alleged counterfeiting and money laundering activities.

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