The regime of Syrian President Bashar al-Assad warned Sunday that a series of powerful Israeli airstrikes near the Syrian capital opened the door to “all the options,” underscoring the possibility that Syria’s civil war could spill across regional borders.

Assad’s cabinet held an emergency meeting Sunday after explosions lit up the sky on the outskirts of Damascus on Friday and early Sunday.

Syrian state media said the air attack had targeted a military and scientific research facility. The Israeli military declined to comment on the strikes, but the Associated Press quoted an anonymous Middle East intelligence official as confirming that the research facility was hit.

The airstrikes targeted Fateh-110 missiles, which have precision guidance systems and may have been destined for the Lebanese militant group Hezbollah, the official said.

Although it was unclear whether Assad’s government would pursue direct military retaliation, the Syrian Foreign Ministry said the attack proved that Israel is collaborating with Syrian rebels.

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“The Israeli attack on military sites in Syria is proof that there is communication between Israel and the terrorist groups who take their orders from al-Qaeda,” the ministry said in a statement broadcast on state television. The government uses the blanket term “terrorists” to refer to its opponents, who range from secular activists to militants linked to al-Qaeda.

Threat of weapons transfer

There was no official confirmation from Israel that it had carried out the airstrikes. Prime Minister Benjamin Netanyahu left Israel on Sunday night for a long-planned trip to China.

In Israel, retired military commanders said they doubted that Syria would retaliate with any lethal force, saying the Assad government does not want to draw Israel deeper into the conflict.

As a precaution, however, the Israeli military announced that it had deployed two Iron Dome missile defense batteries near its northern border in response to “ongoing situational assessments.” Israeli media also reported that airspace over northern Israel and the city of Haifa was closed to civilian flights.

Israeli defense analysts said the airstrikes may have been opportunistic, rather than reflective of an immediate threat.

Israel said last week that it was “very close to 100 percent” certain that Assad’s government had employed chemical weapons against its own people. Although Israel is concerned about the possibility of chemical munitions falling into the hands of extremists, analysts said, its military is more interested in stopping immediate transfers of sophisticated but conventional weaponry from Syria to Hezbollah.

Those weapons include advanced air defense missile systems such as the SA-17, which Israel targeted in a strike in January; Russian-made surface-to-sea missiles, whose 186-mile range leaves Israel’s new natural gas platforms in the Mediterranean Sea vulnerable; and upgraded versions of Iranian ­medium-range Fateh-110 ballistic missiles, which appeared to be the target of the Friday and Sunday airstrikes and could sharply improve Hezbollah’s military capabilities.

“This is the weapons system they do not want to be in Hezbollah’s hands,” said Amos Yadlin, a former head of the Israel Defense Forces military intelligence directorate who is director of the Institute for National Security Studies, a Tel Aviv think tank.

Yadlin said he was not confirming that Israel was behind the strikes, but he added that the Fateh-110 is far more accurate than the Scud missiles that Hezbollah is thought to possess.

Israel made the strategic assessment that Syria would not retaliate in the event of an attack, Yadlin said. “Syria will not react because they know they are in danger from the opposition, and if they start a conflict with Israel, then the military balance will mean them losing some power,” he said.

Regional, sectarian fears

But the airstrikes will probably complicate the politics of a two-year-old conflict that has drawn in regional actors on both sides.

Iran, which backs Assad’s regime and Hezbollah, warned Sunday that Israeli attacks could destabilize the region, Syria’s state news agency reported.

Meanwhile, Syrian opposition groups struggled to find an appropriate response to an assault that may have served their interests logistically but that was carried out by the Jewish state.

“The Syrian [Opposition] Coalition is suspicious of the timing of this attack,” the group, which represents Syrian opposition activists abroad, said in an awkwardly worded statement that blamed both Israel and Assad for the airstrikes. “These strikes have given the regime the necessary time to draw attention away from its crimes and massacres on the Syrian coast.”

Syrian activists said sectarian violence continued for a fourth day Sunday around the city of Baniyas on the Mediterranean coast, where they say pro-Assad forces have executed dozens, possibly hundreds, of Sunnis, including children. The coastal region is the heartland of Assad’s Shiite-affiliated Alawite sect.

The Syrian Opposition Coalition on Sunday released video footage from the area that purported to show bloodied corpses of babies and adults, some of whom had been shot in the head or burned.

Syria’s conflict has grown increasingly sectarian as a predominantly Sunni rebel movement battles a regime dominated by Alawites and backed by Shiites, including Hezbollah. The Lebanese group defines itself primarily as a resistance movement against Israel.

Israeli intelligence reports indicate that Iran has transferred weapons to Syria and on to Hezbollah for years.

“But Israel’s concerns now are heightened because there is a huge stockpile in Syria,” said Mike Herzog, former chief of staff to Israel’s defense minister and brigadier general in the reserves. “And although everyone is focused on chemical weapons, there are many state-of-the-art weapons that could cause huge damage and could fall into the arms of Hezbollah.”

In a statement read to reporters aboard Air Force One as President Obama was en route to Ohio on Sunday morning, White House spokesman Josh Earnest did not comment directly on the strikes but reiterated that the president believes Israel is justifiably concerned about the threat posed by Hezbollah obtaining advanced weapons systems, including missiles.

The United States “is in very close contact” with the Israeli government on a range of issues, Earnest said without elaboration.

The airstrikes highlight rising regional and U.S. concern about the Syrian crisis, especially amid reports that Assad’s government has probably used chemical weapons.

The Obama administration has said that it is examining a range of possible interventions in Syria’s conflict, including the provision of arms to rebels and attacks that would incapacitate the nation’s air defense system.

U.S. officials believe that Iran and Hezbollah are building a network of militias inside Syria to protect their interests in the event that Assad falls. Although the militias are fighting to keep Assad in power, they are also positioning themselves to maintain Iranian supply lines to Hezbollah to continue its fight against Israel.

The conflict has done little to disrupt the supply chain, Mohammed Obeid, a Shiite Lebanese analyst with close ties to the group, said in an interview last month.

Hezbollah “still has it coming in from Syria because Damascus is still controlled by the Syrian army, and the airport is theirs,” Obeid said.

Booth reported from Jerusalem. Karen DeYoung in Washington, Liz Sly and Ahmed Ramadan in Beirut, and Ruth Eglash in Jerusalem contributed to this report.