SEOUL - THE top US and South Korean military commanders agreed on Wednesday to strengthen defences against North Korea's nuclear and missile threats, officials said.

The agreement was reached at talks between Lee Sang Eui, chairman of the South's Joint Chiefs of Staff and his US counterpart Admiral Michael Mullen, Mr Lee's office said.

'The two sides assessed North Korean military threats such as its nuclear and missile programmes and discussed ways to strengthen their allied defence posture,' a Joint Chiefs of Staff official said.

They agreed that both nations should work out 'strategic plans early to specify expanded US deterrence' against nuclear threats, he told AFP on condition of anonymity.

The US stations some 28,500 troops to bolster South Korea's 655,000-strong armed forces against the North's 1.2 million-member military. It also guarantees a 'nuclear umbrella' over its long-time ally in case of atomic attack.

The meeting came ahead of high-level security talks on Thursday between visiting US Defence Secretary Robert Gates and his Korean counterpart. -- AFP