Reports are emerging on Twitter that a Syrian airbase or military airport in Homs is under attack, possibly by US or Israeli aircraft.
But so far there is no confirmation of who is attacking.
The Guardian's world editor Julian Borger tweeted: Pentagon official on Syria: "We are aware of the reports. We have nothing to confirm."
This morning US President Donald Trump said there would be a "big price to pay" after medical aid groups reported dozens of people were killed by poison gas in a besieged rebel-held town in Syria.
At least 40 people were killed, including families found in their homes and shelters, opposition activists and local rescuers say, Reuters reports.
AFP reports that French President Emmanuel Macron accused Damascus of "chemical attacks" against civilians in Syrian rebel enclave of Douma in a call with Trump as the two leaders shared information "confirming" the use of chemical weapons.
AP has added new details:
Syria's state-run news agency says the military's air defenses have confronted a missile attack on air base in central Syria and shot down eight missiles. The report on SANA says the attack on the T4 military airbase in Homs province "is likely to be an American aggression."However, US officials tell AP that the US has not launched airstrikes on Syria.SANA says the attack resulted in a number of casualties.
Earlier there were reports of aircraft and missiles over Lebanon: