The Tomahawk missiles hit Shayrat airfield on Thursday, north of Damascus, CNN reported, citing Pentagon sources. The Bashar Assad regime is believed to have launched the chemical attacks on Iblid province in northern Syria earlier this week which killed at least 82 civilians, including many children.

Trump ordered the attack from his Mar-A-Lago estate in Florida, where he is spending the weekend.

“It is in the vital national security interests of the United States to prevent the spread and use of deadly chemical weapons,” Trump said in a short statement to the media at Mar-A-Lago.

As a result of Assad’s repression and use of chemical weapons among other means, Trump said, “the refugee crisis continues to deepen and the region continues to destabilize threatening the United States and allies.” Trump has said he sees the exodus of refugees from Syria as a threat to the West because of terrorists who may be among them. He has twice sought to bar their entry into the United States; both bids were stayed by the courts.

Trump had indicated earlier that he was considering action.

“Yesterday, a chemical attack — a chemical attack that was so horrific, in Syria, against innocent people, including women, small children, and even beautiful little babies,” Trump said Wednesday during a press opportunity with Jordan’s King Abdullah, a U.S. ally whose nation borders Syria. “Their deaths was an affront to humanity. These heinous actions by the Assad regime cannot be tolerated.”

The Assad regime has denied responsibility and its ally, Russia, has resisted U.N. Security Council action, saying that it is premature to blame Assad for the attack. Trump, in his short statement to the press on Thursday, said there was “no dispute” Assad was behind the attack.

The missile launch represents a sharp departure from the policies of his predecessor, President Barack Obama, who resisted targeting the Assad regime while maintaining some U.S. involvement in the efforts to push back the Islamic State, the terrorist group that is among Assad’s enemies.

It is also a dramatic departure from how Trump campaigned for president, when he lacerated Obama’s predecessor, President George W. Bush, for deepening U.S. involvement in the Middle East, and called for a pullback of U.S. involvement in foreign conflicts.

Just last week, Trump officials suggested that the United States was withdrawing from what was for years a U.S. policy of seeking Assad’s removal.

At his Wednesday press conference, Trump said he was flexible in how he approached policy. “I have that flexibility, and it’s very, very possible — and I will tell you, it’s already happened that my attitude toward Syria and Assad has changed very much,” he said.

CNN reported that Trump informed other countries prior to the attack, although it did not specify whether Israel was among those countries. Israel is concerned about any escalation north of the Golan Heights, which Israel controls; that area, in southwest Syria, is not near the targeted base.

The attack could for the first time in Trump’s presidency rattle what had been warming ties with Russia.