The United States has concluded Russia knew in advance that the Syrian regime would employ chemical weapons in a large-scale attack last week, according to the Associated Press.

Syrian President Bashar al-Assad's regime reportedly ordered the chemical bombings that hit a rebel-held town in the Idlib Province on April 4. At least 80 people were killed, and video footage of women and children fighting to draw breath because of lethal chemical gas spread around the world.

BREAKING: Senior U.S. official says U.S. has concluded that Russia knew in advance of Syria's chemical weapons attack last week. — The Associated Press (@AP) April 10, 2017

According to a senior official, a Russian-operated drone flew over a Syrian hospital while victims sought treatment, and later a Russian-made fighter jet bombed the hospital. The official said the drone's presence revealed that Russia knew the attack was coming:

Hours after the drone left, a Russian-made fighter jet bombed the hospital in what American officials believe was an attempt to cover up the usage of chemical weapons. Until Monday, U.S. officials had said they weren't sure if the drone was operated by Russia or Syria. The senior official said it still wasn't clear who was flying the jet that bombed the hospital. The official said the presence of the drone couldn't have been a coincidence, and that Russia must have known the chemical weapons attack was coming and that victims were seeking treatment.

President Donald Trump responded to the chemical attack on Thursday, when he ordered the firing of 59 Tomahawk cruise missiles at the Al Shayrat airfield in western Syria, where the chemical attack originated.

The Trump administration has stepped up its rhetoric against Russia in the wake of the Syria attack.

Secretary of State Rex Tillerson spoke Monday at a World War II memorial in Italy to issue a warning against countries that "commit crimes against the innocents."

"We rededicate ourselves to holding to account any and all who commit crimes against the innocents anywhere in the world," he said.

United Nations Ambassador Nikki Haley said on Sunday that the administration would not let Russia "cover for this regime anymore."

"This is something to let Russia know, ‘You know what? We're not going to have you cover for this regime anymore. And we're not going to allow things like this to happen to innocent people,'" Haley said on "Meet The Press."