TWO facts explain why there continues to be much discussion in five capitals over whether there has been a Syrian connection behind several recent acts of terrorism -- primarily the attempt to smuggle a bomb aboard an El Al airliner in London on April 17 and the earlier attacks Dec. 27 at the Rome and Vienna airports. One fact is that not much more is conclusively known now about any Syrian connection than was known within the first two days after the April 17 attack. There has been much speculation and much circumstantial evidence, but no new hard evidence.
The other fact is that Israel continues to allege the Syrian connection and has been supported in this contention by United States Vice-President George Bush.
On May 7 Israeli Defense Minister Yitzhak Rabin said at a press conference in Washington that ``we have all reason to believe that it was planned and carried out by part of the established organization of the security and intelligence community of Syria.''
Mr. Bush said on the same day that ``Syria's fingerprints have been on international terrorist acts.''
But the British, German, and Italian governments, which have been working at uncovering the full stories of these and other recent terrorist incidents involving their territory and nationals, have all been careful to avoid pinning clear blame on the Syrian government. The three all insist that there is no ``conclusive'' evidence of a Syrian connection.
The US government, apart from Mr. Bush, has also refrained from accusing Syria. On the contrary, it has kept in touch with the Syrian government and credits it with being helpful in efforts to obtain release of American and other hostages being held presumably by Palestinian or Iranian groups somewhere in the Middle East.
Much turns on whether conclusive evidence of a Syrian connection can be identified. If such evidence can be determined, then President Reagan would in logic find himself required to take direct punitive action against Syria. He would be under pressure to do so by members of his new conservative constituency.
The net effect of taking direct punitive action against Syria would be to make the US a functioning partner of Israel against Syria at a time when tension between the two is high and many believe that a war between them might break out at any moment.
A further effect of identification of a conclusive connection would be to widen the distance between the US and all the Arab countries. The US is already in a state of quasi-war with Libya. Congress is trying to hold up sale of modern US weapons to Saudi Arabia and may be successful in the effort. Punitive action against Syria would seem to confirm Arab suspicions that Washington is now so deeply committed to Israel that it can no longer be on friendly terms with even the most moderate Arab countries.
Much was known about the Syrian connection before these incidents took place, and more is known now. It consists of the known fact that fundamentalist Muslims and activist Palestinians exist generally in Syria, Lebanon, Iraq, and Iran.
There are many groups and factions of such fanatics. The main breeding grounds are the Palestinian refugee camps. The main training centers are in Iran and in the Bekaa Valley region of Lebanon, which lies inside Syrian Army lines.
There has never been any doubt that many activists of these groups have operated in and out of Syria. Nezar Hindawi, who tried to plant the bomb at London's Heathrow Airport, began his trip to London from Damascus.
Abu Nidal, suspected of many a terrorist operation, has an office in Damascus.
But there is one big difference between the Syrian government and the Libyan government. The Syrians have not claimed responsibility for acts of international terrorism, and they have not been caught allowing their government communications system to be used in a terrorist operation.
Col. Muammar Qaddafi of Libya has boasted of his part in such acts. Members of his embassy staffs have taken part in such operations. The US government has deciphered messages between Qaddafi headquarters in Tripoli and agents in Libyan diplomatic missions.
Libya is an avowed promoter and supporter of terrorist activities. Syria denies any connection and has not been caught in an official connection. If President Hafez Assad of Syria has known about terrorist operations mounted from territory under Syrian control, he has practiced the rule that is supposed to cover the covert activities of the CIA, the rule of ``plausible deniability.'' So far, his denials have been plausible, and so far President Reagan prefers to accept them.