Donald Trump vows to respond 'in next 24 to 48 hours' to 'heinous' suspected Syrian chemical attack
Video report by ITV News Washington Correspondent Robert Moore
President Donald Trump is threatening an imminent military strike against Syria, vowing to respond "forcefully" to Saturday's apparent chemical weapons attack on civilians and warning that Russia or any other nation found to share responsibility will "pay a price."
Trump condemned the "heinous" suspected poison gas attack, saying the US will make "major decisions" on how to respond "over the next 24 to 48 hours".
The US president said that if Russia, Iran or the Syrian government were behind the "barbaric" attack, "we'll figure it out".
Prime Minister Theresa May has echoed the US president and has said "if it is the responsibility of Assad's regime then it's yet another example of the brutality and brazen disregard for their people they show."
May will be speaking to her counterparts in the US and France on Tuesday.
It comes as Russia's ambassador to the UN Vassily Nebenzia described the attack as "fake news" and said the US, UK and France had a "confrontational" attitude to Russia.
He also warned armed force by the US in Syria "could lead to grave repercussions".
Speaking at the UN's Security Council meeting on Monday, Mr Nebenzia said "Russia is being unpardonably threatened. The tone with which this is being done has gone beyond the threshold of what is acceptable, even during the Cold War."
Meanwhile, former Prime Minister Tony Blair has told ITV News "if a chemical attack takes place and we have said as an international community this is unacceptable, it is a red line... frankly if you don't take action then you give carte blanche to the Assad regime and their backers, the Russians and the Iranians".
"Since 2013, we've had probably twelve incidents of chemical weapons (in Syria) - so if the world doesn't take a stand then it sends a very clear signal."
Opposition activists say 40 people, including children, died in a rebel-held town near Damascus on Saturday. They blamed Bashar al-Assad's regime, which is closely aligned with Russia.
The Syrian government issued a firm denial, describing the claims of poison as "fabrications".
A statement released by Secretary-General of the United Nations condemned the use of chemical weapons, saying a full investigation would take place.
The statement from António Guterres said: "I am outraged by the continued reports of use of chemical weapons in the Syrian Arab Republic."
It added: "Any confirmed use of chemical weapons, by any party to the conflict and under any circumstances, is abhorrent and a clear violation of international law."
Speaking in the White House Cabinet Room on Monday, Donald Trump said: "It was an atrocious attack, it was horrible.
"We are studying that situation extremely closely. We'll be making some major decisions over the next 24 to 48 hours."
Asked about military action, the president responded: "Nothing's off the table."
The Russian military said it had surveyed the area of the alleged attack and said it found no trace of chemical weapons being used.
The Russian military's Reconciliation Center in Syria has been sending officers into Douma to negotiate with the rebels there and said experts inspected the areas where chemical agents were allegedly used and found no trace of them.
Russia said the team had also inspected Douma's hospital and found no patients with chemical poisoning symptoms.
Mr Trump said such attack "can't be allowed to happen" and that the US was looking "very strongly and seriously" at who was responsible.
"If it's Russia, if it's Syria, if it's Iran, if it's all of them together we'll figure it out and we'll know the answers quite soon," he said.
Medical workers have said woman and children were the main victims among more than 500 cases with symptoms that indicated "exposure to a chemical agent".
On Monday, at least 14 people were reportedly killed in airstrikes on a Syrian military airbase. Russian and Syrian military officials blamed Israel for the airstrike on the T4 base in central Syria, while US officials denied involvement.
Since 2012, Israel has struck inside Syria more than 100 times, mostly targeting suspected weapons' convoys destined for the Lebanese militant group Hezbollah, which has been fighting alongside Syrian government forces.
The alleged use of poison came as Syrian government forces resumed an offensive in the town close to the capital Damascus after a truce collapsed.
In a statement issued via the state-run SANA news agency, the Syrian government said: "The army, which is advancing rapidly and with determination, does not need to use any kind of chemical agents.
The alleged gas attack in Douma comes almost exactly a year after a chemical attack in the northern Syrian town of Khan Sheikhoun killed dozens of people.
That attack prompted Mr Trump to order a missile attack on a Syrian air base. The Syrian government and its ally, Russia, denied any involvement in the alleged gas attack.