The CIA chief has made an unexpected visit to Israel to meet senior political and military figures to discuss the deteriorating security situation in neighbouring Syria.

John Brennan, who took up his post two months ago, met the Israeli prime minister, Binyamin Netanyahu, defence minister, Moshe Ya'alon, military chief of staff, Benny Gantz, and Mossad chief, Tamir Pardo, according to reports in Israel media.

The unannounced meetings followed two Israeli air strikes on weapons stores near Damascus a fortnight ago. Israel has repeatedly warned it will take action to prevent advanced or chemical weapons being transferred to the Syrian regime's Lebanese ally, Hezbollah, or falling into the hands of jihadist groups fighting alongside the Syrian opposition.

According to a report in the Israeli paper Yedioth Ahronoth, the visit stemmed from "the American fear of escalation in the region against the backdrop of [Hezbollah leader Hassan] Nasrallah's threats to act against Israel in the Golan Heights and the American sense that Israel is disappointed by the ineffectuality of the Obama administration with regard to the ongoing deterioration in Syria.

"It is assessed that Brennan was sent to Israel to co-ordinate a joint policy between the two countries and prevent Israel from taking action on its own in Syria."

On Wednesday, the New York Times quoted a senior Israeli official as saying the Jewish state was considering further strikes to prevent the transfer of advanced weaponry to Islamist militants in the region. "If Syrian President Assad reacts by attacking Israel, or tries to strike Israel through his terrorist proxies, he will risk forfeiting his regime, for Israel will retaliate," the official – thought to be a high-level political figure – said.

The Syrian government has warned it will retaliate against further military action by Israel, which would risk embroiling the US ally in a regional conflict.

Two shells landed in the Israeli-occupied Golan Heights this week. An unknown Palestinian group, the Abdul Qader al-Husseini brigades, said it had fired the missiles, which, if true, would make it the first time Israeli-controlled territory had been targeted. "We are avenging all our martyrs that we lost in our war with the Zionist enemy," the brigades said.

Three observers with Undof, the UN peacekeeping force in the Golan, were abducted by Syrian opposition forces and later released on Wednesday, the third such incident in the past two months.