Donald Trump says a suspected chemical attack in Syria will be "met forcefully" hours after Russia warned US military action could cause "grave repercussions".
The US president met with his military leaders in Washington last night (April 9) to discuss their response to the "horrible attack" on Douma, saying a decision would be made "tonight or very shortly thereafter".
Trump did not give a time frame for any retaliatory action but said America could not stand by as such atrocities take place because "we are able to stop it".
He told reporters: "We are the greatest fighting force anywhere in the world.
"We are making a decision as to what we do with respect to the horrible attack that was made near Damascus, and it will be met forcefully. And when, I'm not saying, because I don't like to talk about timing."
His comments came after Moscow's ambassador to the UN warned of the potential consequences to Western intervention in Syria.
Vassily Nebenzia said US attacks on Syria "could lead to grave repercussions", during heated UN Security Council exchanges.
Nebenzia dismissed claims the Syrian regime had used chemical weapons as "fake news", and called for inspectors from the Organisation for the Prohibition of Chemical Weapons to fly to Syria on Tuesday to visit the site of the alleged attack.
US ambassador Nikki Haley accused Russia of having "the blood of Syrian children" on its hands after Trump said that "nothing's off the table" in dealing with the alleged outrage.
She urged the UN to take action, but stressed whether it acts or not, "either way, the United States will respond".
Theresa May said that the UK was considering what action was necessary in response to the "barbaric" attack, which left at least 40 people dead, including children.