WASHINGTON — The airstrike that Israeli warplanes carried out in Syria overnight Thursday was directed at a shipment of advanced surface-to-surface missiles from Iran that Israel believed was intended for Hezbollah, the militant Lebanese organization, American officials said Saturday.
It was the second time in four months that Israel had carried out an attack in foreign territory aimed at disrupting the pipeline of weapons from Iran to Hezbollah. The missiles, known as Fateh-110s, had been sent to Syria by Iran and were being stored at an airport in Damascus when they were struck in the attack, according to an American official.
Syrians with knowledge of security and military matters confirmed the strike, saying that Iran had sent arms and rockets to the Damascus airport intending to resend them to Hezbollah.
Israel officials have declined to publicly discuss the operation. But Israel has repeatedly said it is prepared to take military action to stop the shipment of advanced arms or chemical weapons to Hezbollah. If transferred to Hezbollah, the missiles would extend the organization’s ability to strike targets deep inside Israel.
Syrian forces loyal to President Bashar Assad are believed to possess Fateh-110 missiles. Some American officials are unsure whether the new shipment was intended for use by Hezbollah or by the Assad government, which is thought to be running low on missiles in its bloody civil war with Syrian rebels, now in its third year.
But an American official, who spoke on the condition of anonymity because he was discussing spy reports, said the warehouse that was struck in the Israeli attack was believed to be under the control of operatives from Hezbollah and Iran’s paramilitary Quds force.
Details of the Israeli airstrike are sketchy. Israeli warplanes did not fly over the Damascus airport during the raid. Instead, they fired air-to-ground weapons, apparently using the airspace of neighboring Lebanon.
The Lebanese army said in a statement that Israeli military aircraft ‘‘violated the Lebanese airport’’ on Thursday night and early Friday morning and were flying in circles over several areas of the country.
A spokesman for the Israeli Embassy in Washington declined Friday night to comment on the airstrike, saying only, ‘‘Israel is determined to prevent the transfer of chemical weapons or other game-changing weaponry by the Syrian regime to terrorists, specially to Hezbollah in Lebanon.’’
The Fateh-110 is a mobile, solid-fueled missile that is more accurate and represents a considerable improvement compared with the liquid-fueled Scud missile. Several variants have been produced, and US officials have said it has the range to strike Tel Aviv and much of Israel from southern Lebanon.
In late January, Israel carried out similar airstrikes in Syria against a convoy carrying SA-17 antiaircraft weapons. The transfer of those weapons to Hezbollah would have jeopardized the ability of the Israeli air force to fly in Lebanon.
Israeli officials have also refused to publicly confirm the January attack. But in a February security conference in Munich, a former Israeli defense minister, Ehud Barak, appeared to refer to it as ‘‘proof that when we say something we mean it.’’
The Israeli attack came days after Hezbollah’s leader, Hassan Nasrallah, issued some of his strongest statements yet of support for Assad, edging closer to confirming that Hezbollah is backing him militarily.