Al-Assad is one of the largest and oldest military facilities in Iraq.
It was built in the 1980s for the Iraqi military in desert around 160 kilometers west of Baghdad.
After the US invasion in 2003, it became one of the biggest bases for American troops.
Aside from US and Iraqi forces, the air base has also hosted US-led coalition partners Denmark and Britain.
The base houses about 1,500 troops comprising of both US military and coalition forces.
In December 2018, US President Donald Trump visited al-Assad secretly and briefly, sparking a wave of condemnations from Iraqi officials, with some of them demanding the expulsion of American forces.
During the trip, Trump acknowledged the security concerns about visiting Iraq, saying it was “pretty sad” that he needed such secrecy to see US troops.
“Pretty sad when you spend $7 trillion in the Middle East, and going in has to be under this massive cover with planes all over and all of the greatest equipment in the world, and you do everything to get in safely,” he said.
In December 2019, US Vice President Mike Pence visited al-Assad to celebrate Thanksgiving.