The officials, who declined to be identified because they were discussing intelligence reports, said the attack occurred July 5 near Latakia, Syria’s principal port city. The target was a type of missile called the Yakhont, they said.
Mark Regev, a spokesman for the Israeli prime minister, declined to comment on the strike, as did George Little, the Pentagon spokesman.
The Russian-made weapon has been a particular worry for the Pentagon because it expanded Syria’s ability to threaten Western ships that could be used to transport supplies to the Syrian opposition, enforce a shipping embargo or support a possible no-flight zone.
The missile also represented a threat to Israel’s naval forces and raised concerns that it might be provided to Hezbollah, the Lebanese militia that has joined the war on the side of the Syrian government.
The attack against the missiles came to light after Syrian rebels said that they were not responsible for large explosions at Latakia on July 5, and that a missile warehouse had been hit. American officials did not provide details on the extent of the damage or the number of missiles struck.
Israeli officials have said they would not take sides in the civil war in Syria, but they have made it clear that Israel is prepared to carry out airstrikes to prevent sophisticated weapons from being diverted to Hezbollah.
The strike near Latakia, first reported by CNN, was the fourth known Israeli air attack against targets in Syria this year.
Israel has a longstanding policy of silence on pre-emptive military strikes. In October, Israeli officials declined to discuss reports that Israeli airstrikes had destroyed a weapons factory in Khartoum, Sudan’s capital. Israel has also never acknowledged bombing a nuclear reactor in 2007 that was under construction in Syria.
While the Obama administration has been cautious about getting involved militarily in the Syria crisis, the Israeli attack this month underscored how the conflict has continued to draw in outside powers. Iran has been ferrying weapons to Damascus on flights that pass through Iraq’s airspace and has sent members of its paramilitary Quds Force to help the Assad government.
Thousands of Hezbollah fighters have gone to Syria to fight alongside Syrian government forces, as have Iraqi Shiite fighters, with the strong encouragement of Iran. Russia has continued to supply arms to the Syrian government.
On the other side of the conflict, Qatar and Saudi Arabia have provided weapons to the rebels. The United States has provided “nonlethal” military aid, including food and medical kits, and pledged to expand support to the armed wing of the opposition.
In late January, Israel carried out an airstrike against a weapons convoy that carried Russian-made SA-17 surface-to-air missiles, which Israeli officials believed were to be provided to Hezbollah.
In May, Israeli warplanes conducted two days of airstrikes. Among the targets was a shipment from Iran of Fateh-110 missiles, surface-to-surface missiles able to strike Tel Aviv from southern Lebanon. American officials say the Israelis carried out their airstrikes by launching air-to-ground weapons from planes outside of Syrian airspace.
The Russian decision to deliver the Yakhont missile prompted objections from the Pentagon. Gen. Martin E. Dempsey, the chairman of the Joint Chiefs of Staff, warned in May that it would “embolden the regime.”
For Israel, it represented a serious danger as well. In July 2006, an antiship missile fired by Hezbollah seriously damaged an Israeli ship off the coast of Lebanon.
The Yakhont system is far more sophisticated than the one used in the July 2006 attack, and in recent months there has been speculation that the Yakhont cache in Syria would be Israel’s next target.
During a visit to an army base last week, Israel’s defense minister, Moshe Yaalon, restated Israel’s approach to the Syrian conflict: that it would not get involved except to stop weapons transfers. “We have established red lines when it comes to our own interests, and we are sticking to them,” he said.
Jodi Rudoren contributed reporting from Jerusalem, and Eric Schmitt from Washington.