April 9 (UPI) -- President Donald Trump and Defense Secretary James Mattis on Monday said they're not ruling out the possibility of military action against the Syrian government after a suspected chemical attack killed dozens of civilians this weekend.
Trump told reporters before a Cabinet meeting "there's not much of a doubt" who was behind the attack. On Sunday, he railed against the regime of Syrian President Bashar al-Assad, Russian President Vladimir Putin and Iran for their alleged involvement.
Asked Monday if Putin bears any responsibility for the weekend attack, Trump said, "He may."
"And if he does it's going to be very tough, very tough," the president added. "Everybody's going to pay a price. He will, everybody will.
Trump said his administration would make a decision on how to react to the attack, "probably" by the end of Monday.
"We cannot allow atrocities like that," he said, adding that "nothing is off the table."
Mattis said Monday during a meeting with Sheikh Tamim Bin Hamad Al-Thani, emir of Qatar, he also would not "rule out anything right now".
"The first thing we have to look at is why are chemical weapons still being used at all when Russia was the framework guarantor of removing all chemical weapons, and so working with our allies and partners from NATO to Qatar and elsewhere we are going to address this issue," he told reporters.
Just over a year ago, Trump ordered the firing of 59 Tomahawk cruise missiles to strike a Syrian airfield from where the Assad regime launched another chemical attack on civilians. That attack killed more than 70 people.
Syrian activist and emergency groups said between 40 and 75 people died this weekend after at least one Assad-allied helicopter dropped a barrel bomb of chemicals that left civilians, including children, suffocating.
The Syrian American Medical Society, a non-profit group of healthcare workers in Syria, said 500 people, mostly women and children, sought treatment at Douma healthcare facilities for symptoms consistent with a gas attack.
Meanwhile, on Sunday, Russia and Syria accused Israel of launching a Tomahawk missile strike on the Tiyas air base near the Mediterranean coast. The attack killed more than a dozen people. Syria's state-run SANA news agency also blamed the United States, but the Pentagon denied involvement.
The Israeli military did not deny or confirm whether it launched the missiles.