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
A total of 8,648 sailors died during the largest naval engagement during the First World War, which marks its centenary on Tuesday.
The figures by the Global Slavery Index are a third higher than previously thought.
Sara Di Pietrantonio, 22, died in Rome on Sunday.