Breaking News: We are updating this story as details come in: ISRAEL STRIKES SYRIA!

UPDATED at 5:38am 5/4/13

A Syrian weapons facility was struck early Friday by Israeli warplanes, a U.S. official told Fox News.

A source told Fox News that it is not clear whether the warplanes crossed into Syrian airspace or whether the missiles were fired from across the border.

The strike was confirmed by Israeli officials who said the country’s air force targeted a shipment of “game changing” weapons bound for the Lebanese militant Hezbollah group.

One official told The Associated Press the target was a shipment of advanced, long-range ground-to-ground missiles but was not more specific.

They spoke to the news agency Saturday on condition of anonymity because they were discussing a secret military issue.

It was the second Israeli strike this year against Syria and the latest salvo in its long-running effort to disrupt Hezbollah’s quest to build an arsenal capable of defending against Israel’s air force and spreading destruction inside the Jewish state.

Israeli Prime Minister Benjamin Netanyahu has repeatedly warned in recent weeks that Israel would be prepared to take military action if chemical weapons or other arms were to reach Hezbollah.

When Israeli planes fired on a weapons convoy inside Syria in January, they remained outside Syrian airspace. The convoy was believed to be carrying Russian SA-17 anti-aircraft missiles.

“Israel is determined to prevent the transfer of chemical weapons or other game-changing weaponry by the Syrian regime to terrorists, specially to Hizbullah in Lebanon,” an official from the Israeli Embassy in Washington told Fox News.

Syria’s assistant information minister, Khalaf Muftah, told Hezbollah’s Manar TV that he has “no information about an aggression that was staged,” and said reports of an Israeli air raid “come in the framework of psychological war in preparation of an aggression against Syria.”

Israel has targeted weapons in the past that it believes are being delivered to the Lebanon-based militant group Hezbollah. Earlier this week, Hezbollah leader Sheikh Hassan Nasrallah said his group would assist Syrian President Bashar Assad if needed in the effort to put down a 2-year-old uprising.

In 2007, Israeli jets bombed a suspected nuclear reactor site along the Euphrates River in northeastern Syria, an attack that embarrassed and jolted the Assad regime and led to a buildup of the Syrian air defense system. Russia provided the hardware for the defense systems upgrade and continues to be a reliable supplier of military equipment to the Assad regime.

The airstrike, first reported by CNN, came hours before President Barack Obama told reporters at a news conference in Costa Rica on Friday that he didn’t foresee a scenario in which the U.S. would send troops to Syria. More than 70,000 peoples have died and hundreds of thousands have fled the country as the Assad regime has battled rebels.

The Israeli strike also follows days of renewed concerns that Syria might be using chemical weapons against opposition forces. Obama has characterized evidence of the use of chemical weapons as a “game-changer” that would have “enormous consequences.”

While the U.S. has been providing nonlethal aide to opposition forces in Syria, even stepping up that form of support in recent days, the Obama administration has resisted calls from some American lawmakers to arm the rebels or to work to establish a no-fly zone to aid the insurgency.

On Thursday, however, Defense Secretary Chuck Hagel said the administration is rethinking its opposition to providing arms to the rebels. He said it was one of several options as the U.S. consults with allies about steps to be taken to drive Assad from power. Officials in the administration who spoke on condition of anonymity to discuss strategy said earlier this week that arming the opposition forces was seen as more likely than any other military option.

Obama followed Hagel’s comments by saying options will continue to be evaluated, though he did not cite providing arms specifically. Concerns that U.S. weapons could end up in the hands of al-Qaida-linked groups helping the Syrian opposition or other extremists, including Hezbollah, have stood in the way of that change in strategy.

“We want to make sure that we look before we leap and that what we’re doing is actually helpful to the situation as opposed to making it more deadly or more complex,” Obama said Thursday at a news conference in Mexico.

Pentagon spokesman George Little declined to comment on the report.

Fox News’ Jennifer Griffin, James Rosen and The Associated Press contributed to this report. 

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The officials say the strike occurred overnight Thursday into Friday. They say it does not appear that a chemical weapons site was targeted.

One official says the strike appeared to hit a warehouse.

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UPDATE at 9:18pm——–

The NBC news network cited US officials who said Israel launched airstrikes against Syria on Friday and that Israel’s primary target was a shipment of weapons headed for Hezbollah in Lebanon.

According to the NBC report, a senior US official said the airstrikes were thought to be related to “delivery systems for chemical weapons.”

In Jerusalem, an Israeli defense official declined comment, and a military spokeswoman said, “We do not comment on reports of this kind.”

Syria’s envoy to the UN said on Friday he was not aware of any attack by Israel against his country.

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Just received this update at 8:59pm———–

A source told Fox News that it is not clear whether the warplanes crossed into Syrian airspace or whether the missiles were fired from across the border.

U.S. forces were not involved.

When Israeli planes fired on a weapons convoy inside Syria in January, they remained outside Syrian airspace. The convoy was believed to be carrying Russian SA-17 anti-aircraft missiles.

“Israel is determined to prevent the transfer of chemical weapons or other game-changing weaponry by the Syrian regime to terrorists, specially to Hizbullah in Lebanon,” an official from the Israeli Embassy in Washington told Fox News.

Pentagon spokesman George Little declined to comment on the report.