North Korea stepped up its war of words with the United States Thursday, warning that any pre-emptive attack on the North's nuclear facilities would trigger a "full-scale war". The comments came as Washington considers increasing its military strength in the Far East in reaction to North Korea's nuclear weapons program.

Pyongyang pledges to react to any U.S. strike on its nuclear facilities with "merciless retaliation" and vows to respond to war with "total war."

That warning was made in a commentary carried in North Korea's main newspaper and aired on Radio Pyongyang, according to South Korea's Yonhap news agency.

A North Korean Foreign Ministry official made similar comments to British journalists from the BBC and Guardian newspaper who are visiting Pyongyang. Ri Pyong-gap, the ministry's deputy director, reportedly told the journalists that a decision by Washington to increase its presence on the Korean Peninsula could lead Pyongyang to launch a pre-emptive attack on U.S. forces. Mr. Ri said pre-emptive attacks are not the exclusive right of the United States.

U.S. defense officials said Tuesday they are considering sending reinforcements and additional equipment to American military forces in the Pacific as a warning to Pyongyang. But the Washington denies it is planning any attack on North Korea.

The North's warnings came one day after it claimed to have restarted its Yongbyon nuclear power plant, which can produce plutonium for nuclear bombs. The plant was deactivated under a 1994 pact with the United States that has since collapsed. Under that agreement, a group led by the United States was providing energy aid to the North, while Pyongyang pledged to suspend its nuclear weapons program.

Washington and its allies stopped fuel shipments to the North in December, after Washington revealed that Pyongyang had continued a weapons development program in violation of the 1994 accord. Shortly after that, the North began moving toward reactivating the plant, and expelled United Nations nuclear inspectors.

Pyongyang says it restarted the reactor only to provide electricity for its energy-starved nation, but nuclear experts say the reactor is too small to generate significant amounts of electricity. American officials have called the move "blackmail".

In Washington, U.S. Defense Secretary Donald Rumsfeld said Wednesday that restarting the nuclear program would give the North a troubling option - making nuclear weapons for itself, or selling them to another country or group. He said that is something the world must take very seriously. He also said that the North was mistaken if it felt it could exploit the U.S. preoccupation with Iraq.

Hideya Kurata, a North Korea specialist at Japan's Kyorin University, says the latest moves represent escalating brinkmanship.

He says this situation between the United States and North Korea has been developing for months. He adds that he thinks the two nations' holding talks could be beneficial.

Both countries have expressed a willingness to talk, but so far no meeting has been arranged. Pyongyang has repeatedly demanded the United States sign a mutual non-aggression pact, but Washington has rejected that idea.