Israel promised a "harsh response" on Monday to any attempt by Syrian forces advancing against southern rebel areas to deploy in a Golan Heights frontier zone that was demilitarized under a 1974 Separation of Forces Agreement.
Touring the Israeli Golan Heights, Defense Minister Avigdor Lieberman ramped up threats to use armed force should regime forces encroach on the border. "Any Syrian soldier who will be in the buffer zone risks his life," Lieberman told reporters.
Syrian government forces backed by Russia have launched an offensive in the southern Daraa province and are widely expected to move on rebel-held Quneitra, which is within an area covered by the armistice.
Israel worries that Syria's President Bashar Assad could let its enemies Iran and Hezbollah move forces into the area, giving them a foothold near its border. Tehran and the Lebanese terrorist group both back Assad in the complex conflict.
"For our part, we will honor the 1974 disengagement agreement, and there too we will insist that every last letter be abided by, and any violation will meet a harsh response from the State of Israel," Defense Minister Avigdor Lieberman said.
Assad's conduct in southern Syria is expected to come up in talks in Moscow on Wednesday between Prime Minister Benjamin Netanyahu and Russian President Vladimir Putin.
Russia, whose 2015 intervention in the Syrian civil war turned the tide in Assad's favor, has largely turned a blind eye to repeated Israeli airstrikes in Syria targeting suspected Iranian or Hezbollah emplacements and arms transfers.
But diplomats on both sides say Russia has made clear that it would oppose any Israeli action endangering Assad's rule.
On Sunday night, Syria said its air defense repelled a sortie against the T4 air base in Homs province that reportedly killed nine people. According to foreign media reports, Israel was responsible for the attack.
Jerusalem, in keeping with its customary reticence on such operations, declined all comment.
"Regarding yesterday – I read about it in the newspapers today, and I have nothing to add," Lieberman said on Monday.
"Perhaps just one thing, that our policy has not changed. We will not allow Iran's entrenchment in Syria and we will not allow Syrian soil to be turned into a vanguard against the State of Israel. Nothing has changed. There is nothing new.
"Iran's very presence in Syria is, from our perspective, unacceptable. We are not prepared to accept Iran's presence anywhere in Syria. … As soon as we identify an Iranian presence, we will act."
He said that terrorist "forces affiliated with the [Iran-led] axis are making efforts, under the protection of the [Syrian] regime, to establish infrastructure in the Syrian Golan [Heights]."
Calling these efforts "unacceptable," Lieberman said Israel would "act with force against any terrorist infrastructure that we see and identify in the area."
He said that "from our perspective, the regime is responsible and it will also be held responsible and pay a heavy price for collaborating with axis members and the amount and extent of the forces, in accordance with the [1974] agreement."
Asked by a reporter if he anticipated a time when the Quneitra crossing would be reopened under the U.N.-monitored armistice between Israel and Syria, and whether the two old enemies could establish "some kind of relationship," Lieberman said, "I reckon we are a long way from that, but we are not ruling out anything."
His remarks could foreshadow a more open approach to Assad ahead of Prime Minister Benjamin Netanyahu's talks with Russian President Vladimir Putin in Moscow on Wednesday, his second in two months. At the meeting, Netanyahu will look to maintain Israel's freedom to carry out attacks on Iranians bases inside Syria from the country's air space.
Netanyahu cautioned both Iran and Syria after talks in Jerusalem on Tuesday with Russia's envoy to Syria, Alexander Lavrentiev, and Russian Deputy Foreign Minister Sergei Vershinin. National Security Adviser Meir Ben-Shabbat was also in attendance at the meeting.
"At the meeting [with Putin], the prime minister will make clear that Israel will not tolerate military entrenchment by Iran or its proxies anywhere in Syria, and that Syria must abide meticulously by the 1974 separation agreement," an official statement said.
