A suspected chemical attack caused at least 40 people to suffocate to death, and injured hundreds more, in Syria on Saturday.
On Sunday, US Senator John McCain criticized President Donald Trump for recently saying he is in favor of pulling US troops out of Syria.
McCain said the president's words "emboldened" Syrian leader Bashar al-Assad.
US Senator John McCain on Sunday criticized President Donald Trump for recently saying he is in favor of pulling US troops out of Syria.
McCain said Trump's comments, that he wants to "get out" of Syria and "bring our troops home," emboldened Syrian leader Bashar al-Assad to launch a suspected chemical attack against civilians on Saturday.
"President Trump last week signaled to the world that the United States would prematurely withdraw from Syria," McCain, who is also the chairman of the Senate Armed Services Committee, said in a statement.
"Bashar Assad and his Russian and Iranian backers have heard him, and emboldened by American inaction, Assad has reportedly launched another chemical attack against innocent men, women and children, this time in Douma. Initial accounts show dozens of innocent civilians, including children, have been targeted by this vicious bombardment designed to burn and choke the human body and leave victims writhing in unspeakable pain," he said.
According to reports, at least 40 people suffocated to death and hundreds more were injured from a suspected chemical attack in the rebel-held town of Douma in eastern Ghouta on Saturday. Some estimates put the death toll closer to 150.
Local pro-opposition group Ghouta Media Center said the attack was carried out by a helicopter, which dropped a barrel bomb containing sarin gas. The US State Department confirmed reports of the attack and "a potentially high number of casualties" on Saturday.
Graphic images from the attack have been posted on social media.
President Trump was quick to call out Assad for the violence in a tweet on Sunday: "President Putin, Russia and Iran are responsible for backing Animal Assad. Big price ... to pay." It was also the first time Trump has called out Putin by name on Twitter.
In his statement, McCain acknowledged Trump's quick response on Twitter but said, "The question now is whether he will do anything about it."
McCain said the president needs to "act decisively" in his response to Assad's alleged involvement in the chemical attack, and to "demonstrate that Assad will pay a price for his war crimes."
Some US lawmakers have called on the president to respond militarily to the use of chemical weapons, and have suggested a "targeted attack" on chemical weapons facilities.