As reported by Censor.NET citing The Telegraph, U.S. commander-in-chief - who last year ordered missile strikes on a Syrian airfield after seeing distressing images of civilians poisoned with sarin - looked poised to act again.
"Nothing is off the table," said Mr Trump, when asked whether he was considering military action.
"We are making a decision with respect to what to do with the horrible attack on Syria," he said.
"It will be met, and it will be met forcefully. I won’t say when, as I don’t like talking about timing.
"We’re going to make a decision tonight, or very shortly after, and you’ll be hearing the decision.
"We can’t let atrocities happen. In our world, we can’t let that happen, because of the power of the United States, the power of our country, when we can stop it."
Mr Trump said on Monday night he was consulting with his military and national security advisers, but that he personally had little doubt that the attack was carried out by President Bashar al-Assad's regime, with the possible support of his allies.
"To me there's not much a doubt, but the generals will figure it out," he said.
"So we'll be looking at that barbaric act and studying what's going on. We're trying to get people in there. As you know, it's been surrounded.
"So it's very hard to get people in because not only has it been hit, it's been surrounded. And if they're innocent, why aren't they allowing people to go in and prove? Because as you know, they're claiming they didn't make the attack.
"So 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. So we're looking at that very, very strongly and very seriously."
Syrian activist groups on Saturday said toxic gas inside barrel bombs dropped from helicopters over a rebel-held city in Syria killed dozens of civilians and wounded scores more. Syrian state news said an "official source" denied the allegations.
In the early hours of Monday morning, Syria State TV reported that "several missiles" had been fired at the T4 air base in Homs, in the country's west, adding that it was "likely an attack by the U.S." The Pentagon issued a statement Sunday denying it was conducting air strikes in the region.
On April 9, Russian U.N. Ambassador Vasily Nebenzia said that Moscow had warned the United States of "grave repercussions" if it carries out an attack against Syrian government forces over reports of a deadly chemical weapons attack.
"There was no chemical weapons attack," Nebenzia told the U.N. Security Council.
U.S. Ambassador to the United Nations Nikki Haley told the council that Washington "will respond" to the attack on a rebel-held town in Syria regardless of whether the United Nations Security Council acts or not.
"We have reached the moment when the world must see justice done," Reuters quoted Haley as saying.
"History will record this as the moment when the Security Council either discharged its duty or demonstrated its utter and complete failure to protect the people of Syria," she said. "Either way, the United States will respond."