Trump told reporters at the White House on Monday that the U.S. “cannot allow atrocities like that.”

Trump launched a U.S. missile strike against a Syrian airbase after a chemical weapons attack on Syrian civilians in April 2017, the first direct American attack on Assad’s regime since the conflict in Syria began in March 2011. Rescue workers and activists said dozens of civilians, including children, died in a chemical attack on Saturday amid a renewed assault by Assad’s government on a rebel stronghold near Damascus.

“If it’s the Russians, 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,” Trump said at the beginning of a cabinet meeting Monday. Asked if Assad’s patron Putin shares responsibility for the attack, Trump answered: “He may. If he does, it’s going to be very tough. He’ll pay a price.”

U.S. Assessment

“We are meeting with our military and everybody else and we will be making some major decisions over the next 24 to 48 hours,” Trump said. He later said he expects the U.S. military to assess who was at fault for the attack within a day.

The White House National Security Council’s principals committee held a meeting earlier in the morning to discuss the chemical weapons attack, a person familiar with the matter said.

Tensions in the Middle East ratcheted even higher early Monday with an airstrike by unknown warplanes against a Syrian air base. Russia blamed Israel for the raid; Israel hewed to its customary no-comment policy; and it wasn’t immediately clear whether the facility had a link to the chemical weapons attack.

Trump wasn’t scheduled to be at the NSC meeting Monday but his top national security aides planned to participate, including new National Security Adviser John Bolton, said the person who spoke on condition of anonymity.

Defense Secretary Jim Mattis said he wouldn’t “rule out anything right now” when asked by reporters Monday morning whether the U.S. was considering military actions against Syria including an airstrike.

Trump warned Sunday on Twitter of a “big price to pay” in response to reports of the attack, days after he said he wanted to quickly end the U.S. military presence in the war-torn Middle East country. Trump and French President Emmanuel Macron agreed in a phone call Sunday to “coordinate a strong, joint response” to the suspected attack, according to a White House statement on the call.

While Trump has said he wants U.S. troops out of Syria “very soon,” he posted tweets condemning the attack and charging that Russian President Vladimir Putin and Iran “are responsible for backing Animal Assad.”

The U.S. was also among countries calling for an emergency meeting of the United Nations Security Council, which was expected later Monday. The episode thrust the U.S. and Russia into a new confrontation, with Moscow warning against any military strike and Washington calling for an immediate international response.

“Another humanitarian disaster for no reason whatsoever. SICK!” Trump said on Twitter.

Syria Denies

Syria’s official Sana news agency denied the reports, saying the rapidly advancing army “doesn’t need to use any chemical weapons as the media channels that support the terrorists are fabricating.” It cited an official it didn’t identify.

Sana also reported that there was an attack on a Syrian airbase early Monday. Russia said two Israeli planes attacked the Al Tiyas, or T-4, military base from Lebanese airspace before dawn. Three missiles hit their targets and five others were shot down by Syrian forces, the Russian Defense Ministry said in a statement.

It isn’t clear whether the attack was in response to the suspected chemical weapons use. The T-4 base is the same facility the Israeli military said Iran used on Feb. 10 to launch a drone that penetrated Israeli air space.

Russia, whose military backing of Assad helped turn the course of the war in his favor, denied that Syrian government forces deployed chemical weapons in Douma, according to the Tass news service, which cited Major General Yuri Yevtushenko. Russia plans to send specialists to analyze the scene once militants are expelled from the area, and said the data will refute claims of chemical use, Tass reported.

The Foreign Ministry in Moscow warned that any foreign military strike against Syria over “fabricated” reports of chemical warfare may lead to the “gravest consequences.”