JERUSALEM (AP) ― Syrian rebels control almost all the villages near the frontier with the Israel-held Golan Heights, the Israeli defense minister said Wednesday, bringing the conflict dangerously close to the Jewish state and raising the possibility of an armed clash with the region’s strongest power.

During a tour of the Golan Heights, Defense Minister Ehud Barak gave a scathing assessment of Syrian President Bashar Assad’s forces and said Israel will remain “vigilant and alert.”

“Almost all of the villages, from the foot of this ridge to the very top, are already in the hands of the Syrian rebels,” said Barak, who was accompanied by Prime Minister Benjamin Netanyahu. “The Syrian army is displaying ever-diminishing efficiency.”

The civil war in Syria has renewed tensions over the Golan Heights, a strategic plateau that Israel captured from Syria in 1967. Despite hostility between the two countries, Syria has been careful to keep the border quiet since the 1973 Mideast war.

But in recent days, Israeli troops have fired into Syria twice after apparently stray mortar shells flew into Israel-held territory. On Wednesday, an Associated Press journalist said an Israeli helicopter was patrolling the border area, and gunfire could be heard. The source of the gunfire was not immediately clear.

While it is widely believed that Assad does not want to pick a fight with Israel, there are fears the embattled Syrian leader may try to draw Israel into the fighting in a bout of desperation. Israeli officials believe it is only a matter of time before Syrian rebels topple the longtime leader.

Israeli political scientist Dore Gold, an informal adviser to Netanyahu, said it’s difficult to assess whether Israel is better off with rebels in control along the border.

“The forces fighting the Assad government are made up of diverse elements. And to make a judgment whether Israel should be more or less worried, that would require having a very precise picture of what’s going on there, which we don’t,” he said.

“But it’s no secret that among the Syrian rebels are forces that identify with al-Qaida, and are a cause of concern.”

A buffer zone lines the Israeli border with Syria. Beyond the border on the Syrian side is a 75-kilometer stretch where no military forces other than U.N. forces are permitted.

Israeli military officials said Barak’s assessment depicted a situation that is not entirely new, and that rebels have held those villages for several weeks. It was not clear how many villages the rebels hold along the Golan Heights, which is about 65 kilometers from the Syrian capital of Damascus.

The officials, who spoke on condition of anonymity because they were not allowed to discuss the sensitive information, said the situation is dynamic and could change easily, with the villages returning to Assad’s hands.

Israeli experts said nothing prevents Assad’s forces from entering the villages and retaking them, even ones in the U.N. zone.

“Just like any other place, it is a battleground between the army and the rebels,” said Itamar Rabinovich, the former chief Israeli negotiator with Syria.

He said Israel would likely continue to remain on the sidelines of the fighting because Israeli officials believe Assad will eventually fall and that any support for rebels would backfire.

But privately, “Israel is rooting for the right kind of insurgents,”he said, ones who follow a moderate line and have no links to Islamist extremist groups.

Moshe Maoz, professor emeritus at Jerusalem’s Hebrew University, said the exchange of fire this week was “based on a mistake,” and that if such incidents continued, they would be infrequent.

“The Syrian army doesn’t have any interest in provoking Israel,” he said. “Syria has enough problems.”

The violence in Syria, which has killed more than 36,000 people since the uprising against Assad began in March 2011, threatens to inflame an already combustible region. The fighting already has already spilled into Lebanon, Jordan and Turkey.

On Wednesday, Syrian troops used aircraft and artillery to try to dislodge rebels from a town next to the border with Turkey, as Ankara warned it would retaliate against any airspace violations.

An AP journalist in the Turkish town of Ceylanpinar saw Syrian air strikes in the adjacent Syrian town of Ras al-Ayn, where rebels say they have ousted troops loyal to Assad.

Deadly air strikes began several days ago, and many casualties were taken to Turkey for treatment. Local officials said as many as 30 people have died since Monday. The journalist also saw Syrian forces shelling a wooded area near Ras al-Ayn from where rebels had been firing.

Hundreds of thousands of people have fled the fighting in Syria into neighboring Turkey, Jordan, Lebanon and Iraq.

Another 11,000 escaped to Turkey last week following the surge of fighting at Ras al-Ayn, which is located in the northeastern Syrian province of al-Hasaka, an oil-producing region where the population is mostly Kurdish.

The proximity of the fighting to Turkey has raised fears of an escalation.

Turkish media, including the Anadolu news agency, said several villages west of Ceylanpinar have been evacuated to protect residents from any spillover of the fighting in Syria. About 1,000 people left Mursitpinar, 180 kilometers from Ceylanpinar, after an appeal from the loudspeakers of local mosques.

Ismet Yilmaz, Turkey’s defense minister, indicated that military force would be used in response to any incursions by Syrian aircraft. Last month, Turkish artillery fired on targets in Syria after Syrian shells landed inside Turkey and killed several civilians.

“The necessary response will be given to Syrian planes and helicopters that violate our border,” Yilmaz said.