(NBC NEWS) -- Israeli warplanes launched airstrikes against targets inside Syria on Friday, U.S. officials told NBC News.
It's believed the primary target was a shipment of weapons headed for Hezbollah in Lebanon, they said. A senior U.S. official said the airstrikes were believed to be related to delivery systems for chemical weapons.
An Israeli spokesman in Washington said that Israel would not comment specifically on the reports but said 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."
White House officials referred all questions to the Israelis.
This would be the second time this year Israel conducted airstrikes inside Syria. In January, Israeli fighter jets attacked a convoy of sophisticated anti-aircraft missiles believed on their way to Hezbollah.
Israeli Defense Minister Moshe Ya'alon publicly acknowledged the January airstrike inside Syria in a joint press conference with Defense Secretary Chuck Hagel in Tel Aviv on April 22. Ya'alon said any Syrian delivery of sophisticated weapons to rogue elements like Hezbollah would be a "red line" for Israel and "when they crossed this red line, we operated. We acted."
NBC News Senior Investigative Producer Robert Windrem and White House Correspondent Kristen Welker contributed to this report.