WASHINGTON (AP) -- An Israeli airstrike against Syria was targeting a shipment of advanced missiles believed to be 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. The strike comes as the U.S. considers how to respond to indications that the Syrian regime may have used chemical weapons in its bloody civil war. President Barack Obama has described the use of such weapons as a "red line," and the administration is weighing its options - including possible military action. 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. The Israeli 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. They did not say 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 foreign and defense ministries were not immediately answered. 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." Hezbollah declined comment. Israel has cast a wary eye on Syria's civil war, which has on several occasions spilled over into Israel as well as Turkey, Lebanon and Iraq. The Jewish state is particularly worried about President Bashar Assad regime's stockpile of chemical weapons being transferred to Hezbollah or falling into the hands of Islamic extremists fighting in the rebel ranks.