The escalation of tension comes as relations between Russia and the West have plunged to their worst level in decades, following the poisoning in March of an ex-spy in England that the United Kingdom blamed on Moscow, and alleged Russian interference in the 2016 USA election.
"We can not allow atrocities like that", he said.
"We must not overlook Russian Federation and Iran's roles in enabling the Assad regime's murderous destruction", she said. He added: "Everybody's gonna pay a price".
As he began an evening meeting with military leaders at the White House, Trump promised to "make a decision tonight or very shortly thereafter".
The Syrian government and the Kremlin have denied involvement in the attack. Russian Federation and Syria said there was no evidence that a gas attack had taken place.
Big-power tensions in the Syria conflict, already running high after an apparent chemical weapons attack, ratcheted up as Syria and Russian Federation blamed Israel for air strikes on a Syrian military base that a conflict-monitoring group said had killed 14 people, including fighters from Iran. But if Putin indeed wanted to deal with Trump, why abort all such prospects with a poison gas murder of a has-been KGB agent in Britain, America's foremost ally?
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Washington s main European allies stood by reports blaming Assad.
But Hurd said if differences over Syria lead to a direct military battle between Russia and the United States, Russia would not fare well.
At a photo-taking session in the Pentagon on Monday, Mattis said "the first thing" to consider in how to respond was why chemical weapons are "still being used at all".
The two leaders "strongly condemned the horrific chemical weapons attacks in Syria", according to a White House summary, and they "agreed to exchange information" on the attacks and "coordinate a strong, joint response". Should we just bring the troops home? They include sea-launched cruise missiles aboard ships within range of Syria.
Trump's threat to take action also comes less than two weeks after saying he wanted to withdraw USA forces from Syria.
But here's the thing - activists on the ground have reported multiple chemical weapon attacks since those strikes previous year, including at least three suspected chlorine attacks around where this most recent attack took place in Douma.
The UN Security Council met on Monday to discuss the latest security developments in Syria, in particular the alleged chemical attack in Douma and the airstrikes that followed.
Is it the responsibility of the United States to do something about the use of chemical weapons in Syria? The guided missile destroyer is armed with Tomahawk cruise missiles, the weapon of choice in a US attack one year ago on an airfield in Syria following an alleged sarin gas attack on civilians.
Medical workers and rebel fighters in the area have said around 50 people died in the rebel-held town when a helicopter dropped a container of poison gas. "Area of atrocity is in lockdown and encircled by Syrian Army, making it completely inaccessible to outside world", Trump had tweeted.