(CNN) -- U.S. officials believe Israel has conducted an airstrike into Syria, two U.S. officials told CNN.
U.S. and Western intelligence agencies are reviewing classified data showing Israel most likely conducted a strike Thursday or Friday, both officials said. This is when the United States collected data showing Israel was flying a high number of warplanes over Syria's neighbor, Lebanon.
CNN was first to report news of the strike.
One official said the United States could not confirm the data it had collected represented the warplanes that conducted a strike.
Based on initial indications, U.S. officials said, they do not believe Israeli warplanes entered Syrian airspace to conduct the strikes.
Both officials said there is no reason to believe Israel targeted a chemical weapons storage facility. The Israelis have long said they would strike at any targets that prove to be the transfer of any kinds of weapons to Hezbollah or other terrorist groups, as well as at any effort to smuggle Syrian weapons into Lebanon that could be used to threaten Israel.
The Lebanese army website listed 16 flights by Israeli warplanes into Lebanon's airspace from Thursday evening through Saturday morning local time. And an Israeli surveillance plane entered Lebanese airspace on Friday and left Saturday morning, it said.
The reported incursions provoked a condemnation by Lebanon's president, Gen. Michel Sleiman, the official National News Agency reported.
"Sleiman considered such violations as a continuation of the threatening policy adopted by Israeli enemy officials against Lebanon," it said.
The Israeli military had no comment. But a source in the Israeli defense establishment told CNN's Sara Sidner, "We will do whatever is necessary to stop the transfer of weapons from Syria to terrorist organizations. We have done it in the past and we will do it if necessary the future."