BEIRUT -- Fresh from declaring that they had seized an important military airport and an air defense base just outside Damascus, Syrian rebels Monday said they overran a hydroelectric dam in the north of the country.

It is the latest in a monthlong string of tactical successes that demonstrate the rebels' ability to erode the government's dominance in the face of withering aerial attacks.

On Monday, the conflict was reported to have spilled beyond Syria's border, drawing in Turkish anti-aircraft gunners who were said by the insurgents to have opened fire on a government warplane that appeared to have entered Turkish airspace as it attacked rebel positions in the Syrian town of Atma, just across the Turkish-Syrian border.

According to two anti-government Syrian opposition groups -- the Syrian Observatory for Human Rights and the Local Coordinating Committees -- and a fighter on the ground, who gave his name only as Saado, the Turkish fire deterred an attack on an area that includes a rebel headquarters and a camp for displaced Syrians. But there was no confirmation of the episode from Turkey, and the Syrian state news agency did not refer to the rebels' claims.

Government warplanes also attacked the Bab al-Hawa border crossing at the Turkish border, an area where rebels have enjoyed control for several months, according to an anti-government activist in Turkey. Many displaced Syrians have taken refuge in the area and fled in terror from the fighting, said the activist, who gave his name as Abu Zaki. The strike showed the government's ability to strike at will from the air even in rebel-held territory where it has no control on the ground.

Syria and Turkey have exchanged mortar fire on numerous occasions in recent months, and Turkey, a NATO member, has requested that the alliance provide it with Patriot anti-missile batteries, a possible step toward creating a de facto no-fly zone in northern Syria to protect rebels from Syrian government air attacks.

Turkey has come under criticism from Russia and others for the request.

On Monday, Turkey's military insisted that the Patriot missiles would be used only to defend Turkish territory.

"Deployment of air and missile defense systems is a measure solely against potential air and missile threats that might come from Syria," said a statement posted on the Turkish army's website. "It is out of question for it to be used either for a 'no fly zone' or an offensive operation."