JERUSALEM — Israel was drawn into the Syrian civil war for the first time on Sunday, firing warning shots into the neighboring country after a stray mortar shell from across the border hit an Israeli military post.
The Israeli military said the mortar fire caused no injuries or damage at the post in the Golan Heights, which Israel captured from Syria in the 1967 Mideast war and then annexed. But in recent weeks, incidents of errant fire from Syria to the north have multiplied, leading Israel to warn that it holds Syria responsible for fire on Israeli-held territory.
"A short while ago, a mortar shell targeted an IDF (Israel Defense Forces) post in the Golan Heights," said army spokeswoman Lt. Col. Avital Leibovich. "We answered with a warning shot toward Syrian areas. We understand this was a mistake and was not meant to target Israel and then that is why we fired a warning shot in retaliation."
The Israeli military also said it filed a complaint through United Nations forces operating in the area, stating that "fire emanating from Syria into Israel will not be tolerated and shall be responded to with severity." Israel returned fire with an anti-tank missile.
Nineteen months of fighting and the mounting chaos engulfing the regime of President Bashar Assad have already spilled across borders with Lebanon, Turkey and Jordan. The danger of drawing in Israel as well to a wider regional conflagration is one of the worst-case-scenarios for the civil war.
Violence also flared Sunday on Syria's northern border with Turkey, a common flashpoint. Syrian army forces backed by helicopter gunships and artillery attacked a border area with Turkey after rebels captured a crossing point, activists said.
The Britain-based activist group Syrian Observatory for Human Rights said the Ras al-Ayn border area in Syria's northeast was "under siege" as dozens of rebels tried to hold onto the border crossing.
The upheaval has largely had no direct impact on Syria's bitter foe Israel, and their shared border has remained mostly quiet, as it has been since a 1974 cease-fire.
Still, Israel worries that Syria's civil war could spill across into the Golan — a concern made more immediate by multiple cases of errant fire in recent weeks and Israel's claim that three Syrian tanks entered the demilitarized zone on the plateau this month for the first time in 40 years.
Israeli officials do not see Assad trying to intentionally draw Israel into the fighting, though they have raised the possibility of his targeting Israel in an act of desperation. Israeli officials have repeatedly said it is only a matter of time before Assad's regime collapses.
Over the weekend, Vice Premier Moshe Yaalon said Israel recently conveyed several messages to Syria and Damascus had "conducted itself appropriately." He did not elaborate.
On Sunday, Prime Minister Benjamin Netanyahu told his Cabinet that Israel is "closely monitoring" the border with Syria and is "ready for any development."
Earlier, Defense Minister Ehud Barak warned, "If a shell falls, we will respond."
Israel fears that if Assad's regime is toppled, the country could fall into the hands of Islamic extremists or descend into sectarian warfare, destabilizing the region.
It also is afraid that Syria's arsenal of chemical weapons and missile could fall into the hands of its Lebanese ally, the Hezbollah guerrilla group, or other anti-Israel militants if Assad loses power.
The aftermath of Egypt's revolution has also provided Israel with reason to worry about its frontier region with Syria: Egypt's Sinai desert on Israel's southern border has turned even more lawless since longtime Egyptian President Hosni Mubarak was ousted in February 2011, and Islamic militants are now more easily able to use it as a launching ground for strikes against southern Israel.
Fighting in Syria on Sunday was centered around Ras al-Ayn, in the predominantly Kurdish oil-producing northeastern province of al-Hasaka. An Associated Press cameraman on the Turkish side of the border said he heard explosions and saw plumes of smoke rise on the Syrian side.
On Friday, rebels overran three security compounds in the town, wresting control from regime forces, and the fighting there touched off a massive flow of refugees two days ago.
The violence in Syria has killed more than 36,000 people since an uprising against President Bashar Assad's regime began in March 2011. Hundreds of thousands have fled the fighting into neighboring Turkey, Jordan, Lebanon and Iraq. Another 11,000 escaped Friday into Turkey following the surge of fighting at Ras al-Ayn.
The mayor of the nearby Turkish town of Ceylanpinar, Ismail Aslan, said the number of refugees had slowed significantly on Sunday. But Turkish soldiers at the border turned back some of the refugees who had arrived late last week and wanted to return to Ras al-Ayn, saying the area was not secure.
In Qatar, Syrian opposition groups resumed talks on forging a more cohesive and representative leadership as the U.S. and other Western countries have advocated.
Ali Sadr el-Din Bayanouni, a former Syrian Muslim Brotherhood leader, said opposition groups planned to elect a president and other top officials later Sunday to an umbrella group backed by the U.S. and host Qatar. None of the opposition movements backs dialogue with Assad's regime, he said.
The United States has grown increasingly frustrated with the opposition's inability to overcome deep divisions and rivalries, and has called for a leadership that can rally wider support among activists fighting the Assad regime.
The Syrian National Council, the main opposition faction, is dominated by exiles and has been criticized by the U.S. for not including a broad enough representation, especially of those fighting and dying on the front lines. The SNC said it expects to have 22 seats on the new, 60-member council.
"We need unity for the opposition," said George Sabra, the newly elected leader of the SNC. "This is an important step."
Jamal Halaby in Amman, Jordan, Mehmet Guzel in Ceylanpinar, Turkey, and Abdullah Rebhy in Doha, Qatar, contributed reporting.