The downing of a South Korean jumbo jet with 269 people aboard by a Soviet missile last week has touched off waves of anti-Soviet feeling in Japan and South Korea, but both governments are beginning to take measures to limit reaction.
In Japan, Prime Minister Yasuhiro Nakasone has condemned the Soviet attack in the strongest terms but has played down any leading role by his country in taking action against the Soviets.
Mr. Nakasone told supporters Sunday the act was ''barbarous and inexcusable, '' but he called for caution in official reaction. He said Japan would coordinate all responses to the Soviet Union with the United States and South Korea.
A strong supporter of increased Japanese self-defense power, Nakasone said Thursday's act underlines the Soviet threat off Japanese shores, but he called only for a ''gradual'' buildup of Japanese defense forces to counter the threat.
In Seoul, Foreign Minister Lee Bum Suk rejected calls both from members of the ruling party and the opposition for ''drastic'' action against the Soviet Union and refused to consider a demand that South Korea and Japan close the straits between the two countries to Soviet shipping.
Mr. Lee said sanctions must be studied carefully and carried out only in conjunction with Japan and the US. He did say that South Korea will reexamine its recent overtures to communist countries and may bar Soviet representatives from attending an international parliamentary meeting in Seoul in October.
South Korea had been easing relations with the East bloc in preparation for playing host to the 1986 Asian Games and 1988 Olympics in Seoul, but Mr. Lee said that policy must now be rethought.
In Japan, where relations with the Soviets have been thawing for the first time since the Soviet invasion of Afghanistan three years ago, a renewed cooling is seen as likely.
Both Mr. Nakasone and Foreign Minister Shintaro Abe have been vocal in condemning the shooting down of the Korean airliner, and business leaders have joined in the condemnations.
Observers here say policy is likely to remain very cool, but so far no one is seeing a massive increase in Japanese defense or more efforts to regain control of the Kurile Islands. Occupied by the Soviet Union since World War II, the islands are a continuing thorn in relations between the two countries.
On the defense questions, two schools of thought are emerging. The first is that the Soviet action will galvanize public opinion, generally against an arms buildup here, to greater support of Nakasone's policies. The conflicting school suggests opponents of rearmament will gain ground by playing on Japanese fears of increased Soviet animosity to a stronger Japan.
Some are suggesting the Soviet action was partly due to fears that Japan and the US were trying to break Soviet hegemony over the area of the North Pacific where the plane strayed. If that feeling holds sway, Japanese defense efforts could be thwarted by a public afraid of further antagonizing the Soviets.
What is clear is that neither Japan nor South Korea is likely to take independent action against the Soviets without the firm backing of their American ally.
In that sense, the US response will determine reaction here no matter how strong public anti-Soviet feeling becomes.