NICOSIA, Cyprus — A special envoy of President Reagan left Damascus on Tuesday at the end of a three-day visit designed to improve relations between the United States and Syria after a lengthy diplomatic chill.
The envoy, Vernon A. Walters, a Reagan Administration trouble-shooter and U.S. ambassador to the United Nations, met twice with Syrian President Hafez Assad in the first high-level contact between the two governments in a year.
Walters told reporters that he and Assad talked for several hours. He characterized their meetings as "very useful, very fruitful and very cordial."
Although Walters' mission was essentially exploratory, the upbeat mood afterward suggested that new life was breathed into relations between Washington and Damascus after several years of tension, largely over allegations that Syria was supporting terrorism in the West.
Asked if Assad promised to help in freeing American hostages in Lebanon, Walters replied, "I don't want to prejudice anything by going into that, but I would say that I have other feelings of optimism."
Although the hostage issue clearly topped the Walters-Assad agenda, the apparent breakthrough that was a catalyst for the visit was Syria's decision to close down two liaison offices used by a terrorist group headed by a Palestinian known as Abu Nidal. The Reagan Administration apparently interpreted the move as a significant gesture by Assad, although the Abu Nidal group is believed to be operating just across the border in Syrian-controlled Lebanon.
Last October, the Reagan Administration recalled its ambassador to Syria, William L. Eagleton Jr., imposed limited sanctions and ordered American companies out of Syria after allegations of a direct Syrian role in the attempted bombing of an Israeli airliner in London the previous April. The airliner incident led Britain to sever diplomatic ties with Damascus.
The Syrian government was openly appalled by the damage to its international standing after the plane incident and moved rapidly to improve its image by distancing itself from terrorist groups.
After disclosure of the Iran- contra scandal made it virtually impossible for the United States to deal directly with Iran on the hostage question, the Administration reportedly began looking for another conduit by which to attempt to free the nine Americans who are believed held by various Muslim extremist groups in Lebanon.
State Department officials are said to have been impressed by Syria's quick condemnation of the June 17 abduction of Charles Glass, the American journalist seized near a Syrian checkpoint south of Beirut. Since then, Syria has reportedly intensified pressure on pro-Iranian groups in Lebanon in an effort to obtain the release of the hostages.
According to Western analysts, Assad is seeking political favors from the West as the price for helping with the hostages, a job the Syrians portray as particularly difficult and dangerous.
Specifically, Syria is believed to be seeking from the United States and other Western nations recognition of its political primacy in Lebanon, where it has about 25,000 troops, including 10,000 in West Beirut.
Assad would also like to persuade Washington to move ahead with a proposed international conference on peace in the Middle East on terms acceptable to the Arabs.
No Change of Heart
Many analysts believe that Syria has had no change of heart on the terrorist issue but is preparing for the eventual disruption of relations with Iran, which has supported Syria's economy for several years in exchange for Assad's support in Iran's war with Iraq.
Muslim fundamentalists financed by Iran have become a persistent obstacle for Syria as it attempts to impose peace on Lebanon, and Saudi Arabia has reportedly offered Syria economic aid to persuade it to stop supporting Iran.
Walters, who flew to Damascus from Moscow, heads now for Tokyo and Beijing, where he will seek support for a U.N. Security Council move to force an end to the Iran-Iraq War.