Israel has conducted an air strike in Syria, apparently targeting a building, according to CNN, although there has not yet been any official confirmation.
The network said US officials did not believe Israel had targeted a chemical weapons facility. CBS News cited US sources as saying Israel targeted a warehouse.
But Syrian UN Ambassador Bashar Ja'afari told Reuters, "I'm not aware of any attack right now."
A White House spokeswoman referred questions on the CNN report to the Israeli government.
The Pentagon declined comment.
In Jerusalem, a Israeli military spokeswoman declined to comment.
More top news
The body of Kim Jong-Nam has been returned to North Korea, more than six weeks after he was killed in a targeted attack.
Public sector organisations will have to publish information on any gender pay gap from Friday, in a bid to tackle discrimination.
Remarkably mild night for March