South Korean President Chun Doo Hwan held out little hope today for meaningful progress in talks with North Korea and suggested that the Communist government there views them as part of a strategy to reunify the country by force.

In a three-hour interview, his first with foreign journalists in five years, Chun stressed military tensions and said the North has developed a "seven-day war concept" to blitz the South.

He cited, in ominous terms, new weapons and military cooperation the North is receiving from the Soviet Union.

"In short, the threat of war is real," he said.

His statements came as talks between the two hostile governments have been suspended again. The North cut them off, asserting that joint military maneuvers to be conducted by the United States, which maintains 40,000 troops here, and South Korea poison the atmosphere for detente.

Chun said that Moscow is taking a more active military role in Asia and that South Korea would be an attractive acquisition in its strategic designs in the region. China, in contrast, is exercising a moderating influence on North Korea, he suggested.

Chun's remarks came in an interview with Katharine Graham, chairman of the board of The Washington Post Co., and journalists from The Washington Post and Newsweek magazine. The interview was conducted at the heavily guarded presidential office and residence in Seoul known as the Blue House.

In other points, Chun:

Said he will step down when his current seven-year term expires in 1988 and will oppose efforts before that time to amend the constitution to provide for direct election of the president.

Rejected criticism that his government harasses its opponents. He said the South Korean National Assembly is so free that opposition members take part at times in "free-for-alls" there.

Reiterated an invitation to North Korea to attend the Summer Olympic Games that are to be held in Seoul in 1988 but said the status of North-South Korean dialogue would not affect them.

Called on the noncommunist world to reject protectionism, which he suggested only benefits communist countries.

Chun devoted considerable time to analyzing the balance of forces on the Korean Peninsula, which is one of the most heavily militarized regions in the world. He said North Korea now holds the edge.

Chun said the U.S. military recently had upgraded its estimates of North Korean troop strength from 740,000 to 880,000. The North has deployed more units near the Demilitarized Zone that divides the country and stockpiled about 230 tons of chemical warfare agents, he said.

Chun said the Soviets had delivered 26 MiG23 jets to the North and were expected to raise the figure to 50. He said two new airstrips had been built near the DMZ and cited the reported recent delivery of Soviet-made SA3 antiaircraft missiles.

North Korea and the Soviet Union have moved closer together militarily since the North's president, Kim Il Sung, visited Moscow in 1984, he said. "Russian aircraft fly over North Korean airspace freely," he said. He also cited visits to North Korean ports by Soviet warships.

Chun said that every month, Soviet Badger aircraft conduct tactical reconnaissance flights over the Demilitarized Zone.

Chun depicted this activity as part of a larger Soviet design to increase its military influence in East Asia. He said a third of Moscow's strategic forces are now in the region. He said that if the Soviet Union could take South Korea it could undercut U.S. strategic interests in the region in a single stroke.

"The aggressive policy stance of the two powers seem to coincide," he said, referring to North Korea and the Soviet Union. He indicated that China, the North's other major ally, seems to be playing a moderating role on the peninsula.

"I hope the Chinese leadership will increase its influence in Pyongyang," the North Korean capital, he said, "and I think that can have the effect of preventing catastrophe in this region."

Chun repeated his offer to meet with Kim Il Sung but indicated that he was not optimistic. He noted that the two governments had been at odds for almost 40 years and recalled a bombing in Rangoon, Burma, in 1983 that killed several members of his Cabinet and was blamed on North Korean agents by the Burmese government.

He quoted what he said were words of Kim Jong Il, son of the President Kim and heir apparent to power in Pyongyang, that "South-North talks are a tactical step to a revolutionary goal, a strategy for revolution in South Korea and a union with North Korea."

"They feel these talks can help this goal," Chun said, adding that in the past, "whenever North Korea wanted to talk to us, they had their own reasons."

In 1984, North and South Korea embarked on what has become their most protracted series of talks, touching on sports, economic cooperation, family reunification and political subjects. Few analysts feel that any real progress has occurred, however.

Predicting that international pressure would mount on the North to resume the now-suspended talks, Chun said he hoped that meetings would resume later this year. The North also canceled discussions last year to protest the U.S.-South Korean maneuvers but restarted them soon after the exercises ended.

On domestic politics, Chun said he would leave office in 1988 as required by the constitution that he enacted after seizing power as an Army general in 1980 following the assassination of President Park Chung Hee. He then retired from the military to become president.

"We must set up a precedent of a president handing over his office peaceably to an elected successor," he said. South Korea has never experienced such a transfer since it was founded as a republic in 1948, three years after Korea was divided into U.S. and Soviet occupation zones at the close of World War II.

Chun rejected calls from the chief opposition party for immediate amendment of the constitution to provide for the direct election of the president, rather than the current indirect electoral college system. Chun's opponents say the college is open to manipulation by him, allowing him to choose a successor.

"That issue of constitutional change can be taken up, if there is a need for it, after 1989," Chun said. Opposition groups, however, have rejected that proposal, saying that by then his own man would be settling in for a seven-year term and would not agree to such changes.

Opposition leaders have suggested that even if he resigned, Chun would continue to control the country as the power behind the new president. Asked about his plans after 1988, Chun said he would remain a member of the ruling Democratic Justice Party but saw no role of great influence for himself.

Asked about allegations that he views the opposition as enemies, rather than rivals, Chun said such criticism reflected misunderstanding of politics here. Rejecting charges that the government obstructs and harasses the opposition, he said: "Our opposition members in the halls of the National Assembly act very freely. They exercise their perceived freedom to engage in free-for-alls sometimes."

"Is it done in the United States Congress that a minority member, because he did not get his will, would forcibly occupy the speaker's desk?" he asked. It was an apparent reference to sit-ins staged by opposition members in the assembly in December.

But at the same time, Chun said that in view of South Korea's history of war and its colonization until 1945 by Japan, progress toward democracy here should not be judged by western standards.

Chun said that anti-Americanism that has appeared in South Korea recently is embraced by only a tiny minority. "I speak for 99.9 percent of the country when I say that we feel grateful to the American people. That kind of feeling of friendship is there."

Chun said some students, politicians and clergymen have been exploiting the anti-American issue "for their private political gain." Those who express their views violently, he said, will be "dealt with."

Chun expressed concern that world trade would be harmed seriously by protectionism. South Korea's rush toward industrialization, which has raised officially measured annual per capita income from $82 in 1960 to about $2,000 today, is fueled by exports.

He rejected comparisons of South Korea to Japan as unfair. He said his country has a gross national product one-fifteenth the size of Japan's, is a debtor and not a capital-exporting nation and suffers an overall deficit in its foreign trade, in contrast to Japan's surpluses. However, South Korea rang up surpluses with the United States of about $4 billion in 1984 and $4.2 billion for the first 11 months of last year, and it has been the target of harsh criticism from some members of Congress.

"It's unfair, it's cruel to say, 'Korea is another Japan; let's punish them,' " Chun said.