Hundreds of thousands of South Korean and U.S. troops opened one of the biggest military exercises on the Korean peninsula Thursday. The week-long war games met with angry criticism from North Korea.

U.S. Air Force Lieutenant Colonel Sam Hudpath says the aim of the maneuvers is to test plans to rush reinforcements to South Korea in case of an attack from the North. He insists the activities focus on defending South Korea, not attacking the North. "It is to provide some training and coaching and mentoring for our younger soldiers and it also improves senior leaders' decision-making. It is still a defensive exercise," Colonel Sam Hudpath said.

More than one-million North Korean troops face about 650,000 South Korean and 37,000 American soldiers across a heavily fortified frontier drawn up at the end of the Korean War in 1953.

Colonel Hudpath says the exercises are "going well" so far. But they may show weaknesses in the U.S. military, which is already deeply involved in the Afghan war. Top U.S. military commanders recently told Congress they need more resources to carry out the missions they have been assigned, including defending South Korea.

North Korean radio denounced the maneuvers as a "deliberate provocation to war" conducted by "U.S. imperialist war maniacs" who might spark a conflict and perhaps "inflict nuclear damage" on North Korea.

Professor Kwon Manhak, who studies strategic issues at Kyung Hee University dismisses the North Korean complaint. "They [the North Koreans] have been making that claim for years. I don't think they have reasonable ground for such belief. I think it has been propaganda by North Korea for a long time," Professor Kwon said.

The strained relationship between North Korea and the United States has been particularly tense since President Bush branded Pyongyang part of an "axis of evil" that threatens the world with programs to develop weapons of mass destruction.