September 2, 1983

IC Statements by U.S., page A5. A South Korean airliner missing with 269 people on a flight from New York to Seoul was shot down in the Sea of Japan by a Soviet jet fighter near a Soviet island off Siberia, the United States said yesterday. There were no known survivors of the attack, in which a heat-seeking missile was said to have been fired without warning at the airliner by an interceptor that had tracked it over Soviet territory for two and a half hours. President Reagan expressed ''revulsion'' over what he called ''a horrifying act of violence.'' He cut short his California vacation and called a National Security Council meeting in Washington today to discuss possible reprisals.

After nearly 24 hours of silence, the Soviet Union confirmed tonight only that its jet fighters in the Far East had intercepted and warned ''an unidentified plane'' intruding into Soviet airspace. But it made no mention of any attack on the plane. The statement, by the Government press agency Tass, was the first acknowledgment that Moscow knew about the South Korean airliner that Secretary of State George P. Shultz said was shot down off Sakhalin. (In Washington, the State Department said Foreign Minister Andrei A. Gromyko had sent a message to Mr. Shultz, along the lines of the Tass statement, saying that the plane had violated Soviet airspace, but seeming to disclaim responsibility for the downing of the craft. Mr. Gromyko added that search planes had found ''signs of a possible crash'' near Morenon Island, off Sakhalin.

BFMilitary Analysis Soviet sensitivity over foreign radar penetration of defenses guarding La Perouse Strait south of Sakhalin may have been the motivation for the reported destruction of a South Korean airliner by a jet fighter, according to American officers. In war the strait would be the direct route for the deployment of the Soviet Pacific Fleet into the northwest Pacific, the officers said. Over the last 27 months United States and Japanese intelligence services have reported the expansion of Soviet military power on Sakhalin, on the Siberian mainland and on the island of Etorofu of the Kuril island chain. Etorofu lies 150 miles northeast of Hokkaido, the northern Japanese island. The entire area, one officer said, is of major importance to Soviet strategic planning.

President Reagan today ordered a 2,000-member Marine force into the Mediterranean to position itself off Beirut so ''that all necessary measures'' could be taken to ''assure the safety'' of the 1,370 marines already on shore. Pentagon officials said the additional marine contingent would sail Friday from Mombasa, Kenya, and anchor off Lebanon in about a week. The officials said there were no plans now to send the additional marines ashore. The announcement of the President's decision was made in California, where Mr. Reagan is vacationing, by Larry Speakes, the White House spokesman. It came during a week when two marines were killed and 14 wounded in Beirut as leftist Moslem militiamen battled the Lebanese Army.

The Mesa Petroleum Company said yesterday that it had agreed to sell its stake in the Superior Oil Company back to Superior. The deal marks the third time in the last year and a half that Mesa has come away from a takeover opportunity without an acquisition but with a substantial profit. Mesa acquired about four million shares, or 3 percent of Superior, at an average cost of $34 a share earlier this year. Superior said it would buy the shares back at a price of $42 a share, yielding an indicated profit for Mesa of $32 million.