WASHINGTON:The US says "all options are on the table" in response to a suspected chemical weapons attack in Syria, as western leaders continue to weigh up military action.
White House spokeswoman Sarah Sanders told reporters that a final decision on military strikes had not been taken.
But she said the US holds Russia and Syria responsible for the incident.
Meanwhile warships departed from Norfolk, Virginia amid heightened tensions surrounding the conflict in Syria.
The fleet included the German frigate the FGS Hessen, which will serve in support of maritime security operations.
Earlier, U.S. President Donald Trump warned Russia of imminent military action in Syria over a suspected poison gas attack, declaring that missiles "will be coming" and lambasting Moscow for standing by Syrian President Bashar Al-Assad.
Trump was reacting to a warning from Russia that any U.S. missiles fired at Syria over the deadly assault on a rebel enclave near Damascus would be shot down and the launch sites targeted.
His comments raised fears of direct conflict over Syria for the first time between the two world powers backing opposing sides in the seven-year-old civil war, which has aggravated instability across the Middle East.
President Bashar Al-Assad's government - which receives military backing from Russia - denies being behind any chemical attack.
On the other hand the remaining rebels in Syria's battered eastern Ghouta have surrendered their heavy weapons and their leader has left the enclave for the north.
The Syrian observatory for human rights said rebels handed over their heavy weapons to Russian military police in the town of Douma.