UNITED NATIONS – Syria faced a two-pronged diplomatic dilemma yesterday as the Security Council weighed slapping sanctions against Damascus and Israel considered a military response to the regime’s involvement in Tuesday’s deadly bus bombing.

At the U.N., a resolution circulated among the 15 members of the Security Council denounced Syria and threatened “additional measures” – diplomatic code for sanctions – if it does not immediately remove its 20,000 troops from neighboring Lebanon and stop meddling in that country’s sovereignty.

The resolution, co-sponsored by America and France, is expected to be voted on today.

The resolution was triggered by a measure in Beirut to change the Lebanese Constitution, allowing the continuation of Syria’s domination of its neighbor. The Lebanese Cabinet decided in a hurried weekend session to allow the current president, Emile La houd, a new three-year term despite the constitutionally mandated six-year limit ending in November.

Syria “basically instructed Lebanon not to change the election process, but to abort the election process,” said the American U.N envoy, John Danforth. Past resolutions call for Lebanese sovereignty, he said. “It’s wrong for Syria to occupy [Lebanon] militarily.”

America was adamant on passing the council resolution before the unprecedented change in the Lebanese Constitution is ratified by the Parliament in Beirut, which is expected to convene tomorrow.

The Syrian U.N ambassador, Fayssal Mekdad, called the resolution a “very dangerous precedent” for the U.N., adding it was “a new low” for its sponsors.

In Israel, meanwhile, several officials pointed to the Damascus headquarters of terrorist groups as the source of Tuesday’s dual bus bombing in the southern town of Beersheba that left 16 dead and scores injured.

“Whoever is responsible for using terror against us won’t sleep quietly at night,” the army’s chief of staff, Moshe Yaalon, told a Knesset parliamentary committee. Prime Minister Sharon’s spokesman, Raanan Gissin, told the Associated Press, “The fact that Hamas is operating from Syria will not grant it immunity.”

Mr. Mekdad told The New York Sun that he has “heard such threats before,” and said there was “no basis” for the Israeli allegations. If attacked, he added, Syria “will defend itself.”

Responsibility for the bombing, considered in Israel as a turning point in terrorist activity after a months-long lull, was claimed by a Hamas cell based in Hebron, in the south part of the West Bank. Military intelligence officials in the Knesset briefings contended that the Hebron cell is directly supported by the Syrian headquarters, according to Israeli press reports.

Syria contends that the downtown Damascus headquarters of Hamas and other terror organizations house the “political wings” of the groups, but Israel believes it is directly involved in terror planning.

After a deadly suicide bombing in Haifa last October, which Jerusalem concluded was directed by the Damascus wing of the Islamic Jihad, Israeli bomber jets attacked an empty training camp near Damascus, in what was defined then as a “shot across the bow.” Now, military sources quoted in the Israeli press said that the war against terror cannot be limited to the West Bank and Gaza, and might be widened to include Syrian targets, among others.

On the diplomatic front, yesterday’s proposed resolution was a result of a sustained American effort to confront Syria on its dominance of Lebanon, as well as on the issue of terrorism. President Bush signed the Syrian Accountability and Lebanese Sovereignty Restoration Act last year, threatening Damascus with sanctions if it does not end its support of terrorism and its occupation of Lebanon.

The proposed council resolution, however, does not refer to terrorism. France, the former colonial power in Lebanon and Syria, has been aware of growing anti-Syrian sentiment among Lebanese, a French diplomat told The New York Sun. Paris decided to cooperate with Washington on the resolution, the diplomat added.

The Lebanese prime minister, Rafiq Hariri, a wealthy businessman, is considered a close ally of President Chirac. A longtime rival of President Lahoud, he at first opposed the change in the Lebanese constitution. But after consultation with Damascus he expressed support for extending the presidency. Lebanon has been under Syrian occupation since troops came to put an end to the civil war in 1976.Their presence was affirmed in 1990 by an Arab League agreement known as the TAIF accord.

Several council members who oppose the American-French initiative yesterday seized on that accord, saying that the council should not meddle in the affairs of the two countries.

“There is a question whether the council has jurisdiction on this matter,” Pakistan’s ambassador, Munir Akram, told the Sun.