Time Inc
Updated Apr 07, 2017 @ 9:57 am
Credit: JIM WATSON/AFP/Getty Images

The U.S. fired dozens of cruise missiles at a Syrian airbase Thursday, the first direct assault by American forces against the government of Syrian President Bashar Assad. The attack, ordered by President Donald Trump, was prompted by a deadly chemical attack in northeastern Syria earlier this week that Washington has blamed on Assad.

Here’s what you need to know:

What Happened?

About 60 Tomahawk missiles were launched by American forces targeting the Shayrat airbase in Homs, western Syria. The strike was made from two navy destroyers positioned in the Mediterranean Sea, the Associated Press reports. President Trump spoke to reporters shortly after the attack, calling the assault a “vital national security interest” and calling on other nations to “end the slaughter and bloodshed in Syria.”

Why Were the Missiles Launched?

The U.S. assault came in response to a deadly chemical attack earlier this week in the Syrian town of Khan Sheikhoun, in the country’s northeastern Idlib province. At least 72 people were killed, including some children, making it the deadliest such attack in years in the country.

The Pentagon briefed reporters that it had tracked the aircraft involved in the chemical strike back to the base on radar. U.S. officials say they believe the chemical used was Sarin, AP reports.

The U.N. and Western leaders have blamed the attack on the Syrian government, which has denied using chemical weapons against its own citizens. Russia, a Syrian ally, has also denied the government’s guilt, claiming that the deadly chemical exposure was caused by a rebel-owned arsenal that was struck during airstrikes by Syrian forces. This claim has been widely dismissed by world leaders.

The gruesome chemical attack caused immediate international outrage. “I think what happened in Syria is a disgrace to humanity,” Trump said during a press conference Wednesday. Secretary of State Rex Tillerson suggested, in a sudden shift of U.S. attitudes toward Assad, “it would seem there would be no role for him to govern the Syrian people.”

This story is developing.

This article originally appeared in TIME by Feliz Solomon.