The United States believes Israel has conducted an airstrike into Syria, CNN reported on Friday, citing two unnamed US officials.An IDF spokeswoman said, "We don't respond to reports of this kind.CNN quoted the officials as saying Israel most likely conducted the strike "in the Thursday-Friday time frame" and that Israel's warplanes did not enter Syrian airspace.It said the officials did not believe Israel had targeted a chemical weapons facility. US and Western intelligence bodies were reviewing classified information surrounding the incident, according to the CNN report.There was no immediate confirmation. A White House spokeswoman referred questions on the CNN report to the Israeli government.One source told Reuters that Prime Minister Benjamin Netanyahu had on Thursday night convened his security cabinet in Jerusalem for secret talks - often a sign of imminent action. The source, who would not be identified by name or nationality, did not elaborate on what was discussed at the meeting.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." A third American news network, CBS News, cited US sources as saying Israel targeted a warehouse.In Jerusalem, an Israeli defense official declined comment, and a military spokeswoman said, "We do not comment on reports of this kind."A spokesman for the Israeli Embassy in Washington said, "We cannot comment on these reports, but what we can say is that Israel is determined to prevent the transfer of chemical weapons or other game-changing weaponry by the Syrian regime to terrorists, especially to Hezbollah in Lebanon." Syria's envoy to the UN said on Friday he was not aware of any attack by Israel against his country."I'm not aware of any attack right now," Syria's UN ambassador, Bashar Ja'afari said.The CNN report said that during the time frame of the attack, the United States had collected information showing Israeli warplanes overflying Lebanon. IAF warplanes flew over southern Lebanon at low altitudes on Friday morning, Lebanon's official National News Agency reported.The planes flew over the town of Bint Jbeil in the Nabatiye Governorate of southern Lebanon, according to the report.Israel has made clear in the past that it might intervene to prevent Syrian advanced weapons falling into the hands of militant groups, including Lebanon's Hezbollah, which fought a 34-day war with Israel in 2006. In January this year, "Israel bombed a convoy in Syria, apparently hitting weapons destined for Hezbollah, according to diplomats, Syrian rebels and security sources in the region. Yaakov Lapin contributed to this report.