This is the first time the US has launched a direct attack against the Syrian government, but it has launched thousands of airstrikes in Syria against ISIS since 2014.
If you're not sure exactly why Trump made this choice, and if you're looking for more info on the Syrian conflict in general, these tweets help explain what's going on.
The war in Syria started in 2011.
Hundreds of thousands of Syrians have died.
There are millions of Syrian refugees.
The Syrian government, led by President Bashar al-Assad, has been accused of war crimes.
The US has been active in Syria since 2014 and has conducted thousands of airstrikes against ISIS, not the Syrian government.
Russia is also involved in Syria, and is allies with Assad, who the US just attacked. But Russia doesn't seem to be very angry.
There are a number of actors involved in the conflict with varying alliances, which impacted the response to the strike.
Russia was warned before the strike, Congress was not.
Trump claims he attacked the Syrian government in response to a chemical attack that killed civilians on April 4, but people find this curious since he also doesn't want to help Syrian refugees.
Moreover, after a chemical attack in Syria in 2013, Trump opposed such actions.
Earlier this week, Trump blamed Obama for the chemical attack, despite what he said back in 2013.
Some feel Trump only attacked the Syrian government to increase his popularity and distract people from the scrutiny he's faced regarding his ties to Russia.
There is a lot of debate whether Trump's intervention in Syria will actually help.
It's not entirely clear what happens next.
One thing is for sure: This conflict is very complex and it's not ending any time soon.