BEIRUT -- Syrian warplanes on Monday attacked targets inside eastern Lebanon, the official Lebanese National News Agency reported. It appeared to be the first time since the Syrian conflict began two years ago that the military had used its air force to strike at suspected rebel hideouts across the Lebanon border.
A brief dispatch by the news agency said "warplanes affiliated with the Syrian Air Force" attacked the Wadi al-Khayl Valley area, near the Lebanese border town of Arsal, without specifying whether there had been casualties or damage. The mountainous area, known for its porous border, is considered a haven for Syrian insurgents, and the civilian population there largely opposes Syrian President Bashar Assad.
Al-Manar, the television broadcaster controlled by the Lebanese Shiite group Hezbollah, which supports Mr. Assad, said the warplanes had targeted two barns used by anti-Assad fighters. Agence France-Presse, quoting an unidentified Lebanese security services official, said at least four missiles were fired.
Syrian forces have occasionally fired guns or mortar rounds across the Lebanon border in clashes with anti-Assad fighters but have never before used warplanes to attack suspected rebel positions inside Lebanon.
There was no immediate confirmation of the attack from the Syrian government. But it warned Thursday that its forces might fire into Lebanon because of what it called repeated incursions by terrorist gangs, the official Syrian terminology for the armed anti-Assad opposition. That warning, in a diplomatic protest delivered through the Syrian Embassy in Beirut, complained that "armed terrorist gangs have infiltrated Syrian territory in large numbers from Lebanon."
Lebanon's government, mindful of the long history of entanglements with its neighbor, has sought to remain neutral over the Syrian conflict. But sectarian tensions have been stoked by it nonetheless, aggravated in part by the influx of more than 300,000 Syrians seeking refuge in Lebanon. Many are Sunnis, the Islamic sect that also forms the backbone of the insurgency. Mr. Assad's minority Alawite sect is an offshoot of Shiite Islam.
The warplane attack was at least the third serious border episode in the past few weeks, underscoring how the Syrian conflict has threatened to destabilize the Middle East.
Meanwhile Monday, prospects for ending Syria's civil war through negotiations became even more remote, as the main opposition group tried to set up a rival government to the Assad regime, and the United States said it wouldn't stop its allies from arming the rebels.
The opposition Syrian National Coalition met in Istanbul, Turkey, to elect a prime minister who would run an interim government in Syria's rebel-held areas. The election was initially set for today, but officials then said it might occur later Monday. Similar efforts in the past had been derailed by internal disputes.
Setting up such a government, in a direct challenge to the regime, could harden battle lines even more and close the door to negotiations between the Assad regime and the opposition.
The United States has been cool to the idea of a rival government, saying the focus should be on a political transition. Under a plan endorsed by the international community last year, Mr. Assad's supporters and foes were to propose representatives for a transition government, with each side able to veto candidates.