November 13, 1983

THE United States last week sent a new mediator to the Middle East to take up the quest for reconciliation in Lebanon and security for Israel. Special envoy Donald H. Rumsfeld, who was President Ford's Defense Secretary, flew off to the two countries plus Jordan, Saudi Arabia and Syria, where relations with Washington seemed close to the breaking point. American officials suspect Syria countenanced the terrorists who blew up the Marine headquarters at Beirut airport on Oct. 23, killing 239 Americans. President Reagan has threatened retaliation. But although 30 Navy ships were nearby in the Mediterranean, Washington said last week it had no plans to attack Syria. Damascus, however, announced Syrian antiaircraft batteries had fired on American Navy F-14 jets on reconnaissance missions over central Lebanon. They missed. In Beirut, gunmen fired on the airport, wounding a marine.

Although the city put a halt to the construction of so-called ''sliver'' projects earlier this year, the tall, narrow apartment buildings towering over others on their blocks will continue to rise throughout midtown as developers who had started work before the ban was adopted finish their projects. The new law says that buildings on lots up to 45 feet wide in primarily residential areas can be no taller than either the abuting buildings or the distance from its property line to that of buildings or structures directly across the street, whichever is greater.

Until last year, Whittier House, the 19th century mansion and adjoining town house at 172 and 174 Grand Street in Jersey City, was the home of the Jersey City Boys Club until last year. Then a fire forced the club out.

LESS than three months before American athletes will compete in the XIV Winter Olympics at Sarajevo, Yugoslavia, the United States Olympic Committee faces the most demanding period in its history. Raising $80.1 million to meet budget requirements, implementing new drug-testing procedures, monitoring its financial partnership with the Los Angeles Olympic Organizing Committee and dealing with an uncertain political climate are only a few of the complex pressures that will confront the U.S.O.C. in the coming months. ''It's important that we have the best-prepared team and do exceedingly well in the 1984 Olympic Games,'' F. Don Miller, the executive director of the committee, said recently. ''By doing well, it will provide an incentive and a motivating factor for promoting the youth of our country to participate in amateur sports.'' But as the role of the U.S.O.C. has expanded from what some United States officials once termed a ''travel agency'' to the umbrella organization for amateur sports in the United States, the committee has been criticized for either trying to do too much in dealing with international federations and national governing bodies or not doing enough for American athletes. Such criticism often is based on comparisons of the role of the U.S.O.C. with successful state-subsidized sports programs in the Soviet Union, East Germany and other Eastern European countries.

President Reagan was preparing for a three-hour tour today in the grim demilitarized zone between the two Koreas, planning to address American troops and look by binoculars at what he called the forces of ''hatred and oppression'' across the demarcation line in North Korea. An advance battalion of news personnel crowded into this camp nestled in foothills not far from North Korean military outposts as Mr. Reagan prepared to depart from Seoul, the South Korean capital, 26 miles to the south. ''You are on the front lines of freedom,'' the President declared in remarks prepared for the visit. ''The Communist system to the north is based on hatred and oppression.''