They also help the Iraqi Armed Forces maintain their fleet of F-16 Falcon fighter jets.
However, contractor conduct at the base has been brought under severe scrutiny as of late, with both the US Government Accountability Office and the US Department of Justice investigating misconduct there, including mismanagement, bigoted abuse by contractor staff, and the possibility that former Iraqi Prime Minister Nouri al-Maliki might've been bribed to award lucrative contracts at the base.
The US also evacuated hundreds of non-emergency diplomatic staff from its Baghdad embassy last month, citing unspecified threats from Iran, according to ABC.
Last Friday, several mortar shells landed inside the base, lighting brush afire but not injuring anyone.
On Monday, three rockets fired from a Katyusha system landed in Camp Taji, northwest of Baghdad, where US troops are stationed.
Then on Wednesday, a rocket that Iraqi police said was fired from a Katyusha fell about 100 meters short of the ExxonMobil headquarters it was aimed at in the southern Iraqi city of Basra.
No one has claimed responsibility for the attacks.
Thursday evening, US President Donald Trump called off imminent airstrikes on Iranian missile and radar sites at the last moment, following a controversial shootdown of a US reconnaissance drone in the Gulf of Oman.
US Central Command maintains the drone was in international airspace, but the Iranian Islamic Revolutionary Guard Corps, which fired the anti-air missile, says the drone had veered into Iranian airspace.
On Friday, IRGC Aerospace Force commander Brig.
Amir Ali Hajizadeh, noted in a speech on Iranian television that US assets in the region were "susceptible" to attack in the event of a shooting war between the two countries.
"US forces in the region were a threat, but they are now an opportunity," Hajizadeh said.
"They do not talk about war with Iran, because they know how susceptible they are."