President Donald Trump said Monday he will make a decision on how to respond to an apparent chemical weapons attack by the Syrian government in the next 48 hours. And he said another U.S. military strike is possible.

But Trump also told reporters a decision could come later Monday, saying “nothing is off the table” when asked specifically about the possibility he would order a second round of U.S. military strikes in the conflict-torn country in a year.

“We’ll be making that decision very quickly. Probably by the end of today,” he said. “We cannot allow atrocities like that. … It was atrocious. It was horrible. This is about humanity and it can’t be allowed to happen.

“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,” he told reporters during a Cabinet meeting at the White House.

The U.S. president last year ordered cruise missile strikes on targets in Syria after the country’s president, Bashar al-Assad, ordered a chemical weapons strike that killed civilians. Trump was moved by images of dead children, aides said last year.

[Putin, Iran ‘Responsible’ for Assad’s Actions, Trump Says]

Lawmakers have been weighing in about the Syrian government’s chemical attack, which appears to have killed nearly 50 people, including many women and children and left dozens more injured. Some want Trump to strike Assad government targets while others are calling on the international community to respond as one and the Trump administration to deliver them a longterm Syria strategy to end years of fighting there.

Asked if U.S. officials have told him that Assad’s government, which is backed by Russia and Iran, might not have carried out the chemical attack, Trump responded: “To me there’s not much a doubt, but the generals will figure it out.”

He is slated to huddle with his top military officials Monday evening for a long-planned strategy briefing and dinner.

On Sunday, the president called out Russian President Vladimir Putin — something he rarely does — and Tehran for their support of Assad. He said both have “responsibility” for his actions and should pay a “big price.” He reiterated Putin should be punished for supporting Assad on Monday.

Many dead, including women and children, in mindless CHEMICAL attack in Syria. Area of atrocity is in lockdown and encircled by Syrian Army, making it completely inaccessible to outside world. President Putin, Russia and Iran are responsible for backing Animal Assad. Big price…

— Donald J. Trump (@realDonaldTrump) April 8, 2018