An Israeli airstrike against Syria was targeting a shipment of advanced missiles bound for the Lebanese militant group Hezbollah, Israeli officials confirmed Saturday.

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.

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The officials said the attack took place early Friday and was aimed at sophisticated "game-changing" weapons, but not chemical arms. One official said the target was a shipment of advanced, long-range ground-to-ground missiles but was not more specific.

It was not immediately clear where the attack took place, or whether the air force carried out the strike from Lebanese or Syrian airspace.

The Israeli officials spoke on condition of anonymity because they were not authorized to disclose information about a secret military operation to the media.

U.S. officials had earlier confirmed the airstrike but said only that it appeared to have hit a warehouse.

Calls to the Israeli military and defense ministry were not immediately answered.

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 that would upset the balance of power with Hezbollah were to reach the Islamic militant group.

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."

It's not the first time since Syria's crisis erupted in March 2011 that Israel has intervened struck inside Syria.

In January, the Israeli air force is believed to have targeted a shipment of advanced SA-17 anti-aircraft missiles bound for Hezbollah. Israel has not formally admitted to carrying out that airstrike, though officials have strongly hinted they were behind the attack.

The airstrikes follow decades of enmity between Israel and allies Syria and Hezbollah, which consider the Jewish state their mortal enemy. The situation has been further complicated by the civil war raging in Syria between President Bashar Assad regime and rebel brigades seeking his ouster.

The war has drained Assad's military and threatens to deprive Hezbollah of a key supporter, in addition to its land corridor to Iran. The two countries provide Hezbollah with the bulk of its funding and arms.

Israel and Hezbollah fought an inconclusive 34-day war in 2006 that left 1,200 Lebanese and 160 Israelis dead.

While the border has been largely quiet since, the struggle has taken other forms. Hezbollah has accused Israel of assassinating a top commander, and Israel blamed Hezbollah and Iran for a July 2012 attack on Israeli tourists in Bulgaria. In October, Hezbollah launched an Iranian-made reconnaissance drone over Israel, using the incident to brag about its expanding capabilities.

Israeli officials believe that Hezbollah's arsenal has markedly improved since 2006, now boasting tens of thousands of rockets and missiles and the ability to strike almost anywhere inside Israel.