The United States is basing more heavy bombers near North Korea and will formally protest the communist nation's "reckless actions" in using MiG fighters to intercept a U.S. surveillance plane, officials said.

Shifting the military aircraft toward northeast Asia was described "as a prudent gesture to bolster our defense posture and as a deterrent" by Defense Department spokesman Lt. Cmdr. Jeff Davis on Tuesday.

Other Pentagon officials said the deployment includes sending B-52 bombers to the U.S. Pacific territory of Guam. The order was issued Friday, well before Sunday's incident in which North Korean jets came within 50 feet of a U.S. RC-135S surveillance plane over the Sea of Japan, they said.

"These (U.S.) moves are not aggressive in nature," Davis said.

Military officials said Tuesday the United States was reviewing its options in light of the gravity of Sunday's incident, one of the most dangerous military provocations in a monthslong standoff over North Korea's nuclear weapons program.

Those options could include having U.S. fighter jets escort similar flights, a senior military official said. The United States has not suspended the flights and does not plan to, officials said.

White House spokesman Ari Fleischer said President Bush would consult with allies to determine the best way to protest the incident. Fleischer said Bush believes the North Korean standoff can be solved through diplomacy.

"North Korea continues to engage in provocative and now reckless actions," Fleischer said. "And North Korea engages in these actions as a way of saying, `Pay me.' That will not happen."

During Sunday's incident, four North Korean fighters neared the Air Force plane, which was flying 150 miles off the Korean coast, the Pentagon said. The North Korean fighters scanned the unarmed U.S. plane with targeting radar, Davis said.

The North Korean fighters were carrying heat-seeking missiles that did not require radar locks to hit their targets, a military official said Tuesday.

That means the MiGs could have fired on the slower U.S. plane without further warning. The North Koreans shot down a U.S. Navy EC-121 surveillance plane in 1969, killing all 31 Americans aboard.

The Pentagon has been hesitant in the past to arm or escort its surveillance flights, which military officials say always operate legally - well inside international airspace. Escorting the surveillance flights, some officials argue, would undercut the U.S. assertion that the flights are not military threats.

Tensions with North Korea began to escalate in October, when the United States said North Korea had admitted having a program to enrich uranium for nuclear weapons. Since then, the United States has refused direct talks with Pyongyang and cut off fuel oil shipments under a 1994 agreement that banned North Korean nuclear weapons development.

The United States believes North Korea has one or two nuclear bombs.

North Korea has ejected United Nations nuclear monitors, withdrawn from the Nuclear Non-Proliferation Treaty and restarted a nuclear reactor that U.S. officials say was designed to produce plutonium for nuclear weapons. Pyongyang says the reactor is to generate electricity.