Trump’s remarks came just days after his administration said it would no longer seek the ouster of Bashar al-Assad. The U.S., France and Britain accuse the Assad government of carrying out a chemical attack. A spokesperson for Russian President Vladimir Putin called the gassing of civilians a “dangerous and monstrous crime” but did not name anyone as the perpetrator. At the United Nations, U.S. Ambassador Nikki Haley told the Security Council Wednesday the U.S. was prepared to take unilateral action against Syria.

Ambassador Nikki Haley: “When the United Nations consistently fails in its duty to act collectively, there are times in the life of states that we are compelled to take our own action.”

Ambassador Haley held photographs of Syrian children killed in Tuesday’s gas attack, asking, “How many more children have to die before Russia cares?” The journalistic monitoring group Airwars reports over 700 children have been killed in U.S. coalition airstrikes in Iraq and Syria since August 2014.