WASHINGTON - US Defence Secretary Robert Gates said on Thursday that North Korea's famine has reduced the threat posed by its armed forces.

'This is an army that's starving,' Mr Gates said at a town hall meeting with soldiers at the US Army's Fort Drum in upstate New York.

'The famine of the mid-1990s has affected the physical and even intellectual development of those that are now coming into the zone who would be eligible for military service,' he added.

The 1990s famine killed as many as 1 million of North Korea's then 22 million people.

'This is a country whose conventional forces and capabilities are really, I think, declining.' The US defence chief's comments follow months of heightened tension over North Korea, which has tested a nuclear weapon and test-fired missiles in defiance of international efforts to persuade Pyongyang to end its nuclear program.

'They are developing these nuclear weapons. They are developing longer-range missiles. We're watching them very closely and I hope they don't make any stupid mistakes,' Mr Gates told his audience from the Army's 10th Mountain Division.

North Korea's harsh rhetoric has raised concern about the danger of a shootout along the Demilitarized Zone border with South Korea that could ignite a broader battle involving more than 1 million troops on both sides of the zone.

The United States has about 28,500 troops stationed in South Korea.

But Mr Gates said an actual invasion by North Korea would be met by a South Korean military that has greatly expanded in size and capability in recent years.

'What you would see would be the South Koreans taking the bulk of the ground attack and our Navy and Air Force would be providing the principal strategic reserve in terms of supporting those operations,' he said.