Defense Secretary Harold Brown said yesterday the U.S. ordered a modest redeployment of its military force in and around South Korea in the wake of the assassination of President Park Chung Hee, but does not plan to alter long-range plans for military withdrawal from the country.

Brown, speaking on "Meet the Press" (NBC, WRC), said two early warning aircraft were dispatched to Korea and an aircraft carrier task force was shifted closer to the Korean coast from its normal patrol position between Korea and Japan.

The planes, known as airborne warning and control system (AWACS) craft, are able to spot movements of other aircraft up to 200 miles away, said Brown, and can also control large numbers of combat aircraft if needed.

Brown added that President Carter's decision earlier this year to hold off until 1981 on the withdrawal of the Army's 2nd Division from Korea remains in effect.

He described the situation in South Korea as "stable and calm. Constitutional processes are being followed and the military clearly is supporting the civilian government."

State Department officials have said there appears to be no immediate reaction from North Korea to Park's assassination on Friday.

In an official announcement yesterday, the South Korean government reversed field and said Park had been assassinated, not slain accidently, by Kim Jae Kyu, the director of the South Korean CIA. Five of Park's bodyguards also were killed and a sixth was wounded.

Brown said he was not surprised at the new version of the shooting that was announced yesterday.

"It does not come as news to me that this is one possible explanation," the defense secretary said. He added that "further time and further investigation would be necessary before an interpretation emerged."

"We have no information that would contradict the Republic of Korea accounts of what happened," said Brown. "Clearly, there has not been a coup."

U.S. military forces in South Korea were put on a "higher level of alert" within hours after the shooting took place, Brown said.

Although there have been no apparent moves by the North Koreans during the unsettled political situation in the south, Brown said the deployment of the additional forces in South Korea was undertaken to deter "external interference or adventurism."

The defense secretary also called the recent Soviet offer to unilaterally put out 20,000 troops and 1,000 tanks from East Germany "a constructive move." If such a withdrawal is accomplished, Brown said, both sides should pursue further mutually negotiated force reductions.

Brown rejected a second Soviet proposal to cut back Soviet missiles in exchange for an end to Western plans to deploy similar missiles in Western Europe.But he said that if the Western missiles are deployed there may be a reduction in the number of shorter range-rockets now stationed in Europe.