Syrian warplanes on Monday bombed a security building that had been taken over by rebels along the Turkish border, killing at least one person, wounding 20 more and sending dozens of civilians fleeing across the frontier, a Turkish official said.
The conflict also spilled into Syria's eastern neighbor, Lebanon, after Lebanese troops exchanged fire with rebels across the border late Sunday. Violence from Syria's 20-month-old uprising has on several occasions touched neighboring countries, fueling concerns that the Arab Spring's longest and deadliest revolt could touch off a regional war.
The violence came as Russian President Vladimir Putin, a close ally of Damascus, headed to Turkey for talks likely to be overshadowed by the two countries' differences over Syria. Ankara is expected to press Putin to stop backing President Bashar Assad's regime. Moscow has shown no inclination to relinquish its support for its last Middle East ally, whom it has shielded from international sanctions and continued to provide with weapons amid the escalating civil war.
An official from the mayor's office in the Turkish border town of Ceylanpinar said a Syrian jet targeted a security building that had been overrun by rebels, dropping two bombs on an area some 300 meters (yards) from the Turkish border.
Turkish ambulances ferried at least 21 wounded Syrians from the border to Ceylanpinar's hospital, the official said on condition of anonymity in line with Turkish government policy. One of the wounded later died in the hospital, the official said, adding that witnesses in Ras al-Ayn told him more than a dozen people were killed in the bombing.
Television footage from Turkey's Anadolu agency showed a large plume of smoke rising over the town, and dozens of Syrian civilians were also seen fleeing into Turkey after crossing through a barbed wire fence at the border.
Lebanon's state-run National News Agency said that Lebanese soldiers stationed near the village of Qaa in the Bekaa Valley returned fire into Syria after "armed men" shot at them from across the frontier late Sunday. The agency quoted a statement from the Lebanese army that said there were no casualties.
In Syria, activists reported heavy fighting between rebels and regime troops in the southern suburbs of Damascus as the army pressed an offensive to regain lost territory near the capital, including two air bases.
The Britain-based Syrian Observatory for Human Rights said the fighting Monday was concentrated in districts just south of Damascus, including in areas near the airport. The Observatory, which relies on reports from activists on the ground, said there were casualties.
The Damascus suburbs have been opposition strongholds during the 20 months of fighting aimed at toppling Assad. The fighting over the past few weeks in and around Damascus — the seat of Assad's power base — has been the most serious in the capital since July, when rebels captured several neighborhoods before a swift government counteroffensive swept them out.
The SANA state news agency said a car bomb detonated near the Engineering College in Aleppo, wounding four people. The report said "terrorists" — a term the regime uses for rebels — were responsible for the attack in the northern city that has been a major front in the civil war since the summer.
Also on Monday, U.S. Secretary of State Hillary Rodham Clinton reiterated President Barack Obama's declaration that Syrian action on chemical weapons was a "red line" for the United States that would prompt action. She didn't address news reports suggesting fresh activity at Syrian chemical weapons depots, but insisted that Washington would address any threat that arises.
Syria is believed to have several hundred ballistic surface-to-surface missiles capable of carrying chemical warheads.
Its arsenal is a particular threat to American allies Turkey and Israel, and Obama singled out the threat posed by the unconventional weapons earlier this year as a potential cause for greater U.S. involvement in Syria's civil war. Up to now, the United States has opposed military intervention or providing arms support to Syria's rebels for fear of further militarizing a conflict.
More than 40,000 people have been killed since the Syrian revolt started in March last year.
While the actions of Assad's government have been deplorable, Clinton said chemical weapons would bring them to a new level.
"We have made our views very clear: This is a red line for the United States," Clinton told reporters in Prague.
"I'm not going to telegraph in any specifics what we would do in the event of credible evidence that the Assad regime has resorted to using chemical weapons against their own people. But suffice it to say, we are certainly planning to take action if that eventuality were to occur."
Syria's Foreign Ministry denied Damascus has chemical weapons, and said in a statement to Syrian state TV that it would never use them against its own people, even if it had them.
Surk reported from Beirut. Associated Press writer Bradley Klapper in Prague contributed to this report.