An IDF soldier looks into southern Syria from the Israeli side of the border. Photo: IDF via Wikimedia Commons.

Israel launched Patriot missiles in what it described as a successful interception of a Syrian warplane that penetrated its airspace on Tuesday, but Damascus said the jet was fired on as it took part in operations against rebels on Syrian territory.

The incident took place over the Golan Heights, a strategic plateau between the two old foes and whose Israeli side has been on high alert as Syrian government forces close in with Russian support to regain rebel-held ground.

For the second time in as many days, Israeli sirens sounded on the Golan and witnesses saw the contrails of two missiles flying skyward. The military said it fired Patriots at a Syrian Sukhoi jet “that infiltrated into Israeli airspace.”

The warplane was “intercepted,” the military said in a statement without elaborating. Israel‘s Army Radio said the Sukhoi was shot down, may have crashed on the Syrian side of the Golan, and that the pilot’s condition was unclear.

Syrian state media said, however, that a Syrian warplane had been “targeted” by Israel and hit while conducting raids in Syrian airspace.

“The Israeli enemy confirms its support for the armed terrorist groups and targets one of our warplanes, which was striking their groups in the area of Saida on the edge of the Yarmouk Basin in Syrian airspace,” the official news agency SANA quoted a military source as saying.

The Israeli military statement said the Syrian plane had crossed two kilometers (one mile) into the Israeli side of the Golan, but appeared to acknowledge that its mission was related to the civil war next door.

“Since morning hours, there has been an increase in the internal fighting in Syria, including an increase in the activity of the Syrian Air Force,” the statement said.

It said Israel would “continue to operate against” any breach of a 1974 UN armistice deal that established buffer zones on the Golan.

Israel worries that Syrian President Bashar al-Assad might try to defy the demilitarization regime or allow his Iranian and Lebanese Hezbollah reinforcements to deploy near the Golan.

The intensifying Israeli-Syrian tensions have prompted intercession by Moscow, which sent its top diplomat and top general on Monday for talks with Israeli Prime Minister Benjamin Netanyahu. Israeli officials said Netanyahu rebuffed as insufficient a Russian offer to keep Iranian forces 100 kilometers (62 miles) from the Golan lines.