A look at Al Udeid Air Base, US military site in Qatar that Iran attacked

Iran retaliated Monday for the US attacks on its nuclear sites by targeting Al Udeid Air Base, a sprawling desert facility in Qatar that serves as a main regional military hub for American forces.

A US defence official says no casualties have been reported.

As of this month, the US military had about 40,000 service members in the Middle East, according to a US official. Many of them are on ships at sea as part of a bolstering of forces as the conflict escalated between Israel and Iran, according to the Washington-based Council on Foreign Relations research and policy centre.

Bases in the Middle East have been on heightened alert and taking additional security precautions in anticipation of potential strikes from Iran, while the Pentagon has shifted military aircraft and warships into and around the region during the conflict.

The US has military sites spread across the region, including in Qatar, Bahrain, Iraq, Israel, Egypt, Jordan, Kuwait, Saudi Arabia, Syria and the United Arab Emirates.

Here's a look at Al Udeid Air Base in Qatar:

Al Udeid hosts thousands of service members

The sprawling facility hosts thousands of US service members and served as a major staging ground for the wars in Afghanistan and Iraq. At the height of both, Al Udeid housed some 10,000 US troops, and that number dropped to about 8,000 as of 2022.

The forward headquarters of the US military's Central Command, Al Udeid is built on a flat stretch of desert about 20 miles (30 km) southwest of Qatar's capital, Doha.

Over two decades, the gas-rich Gulf country has spent some $8 billion in developing the base, once considered so sensitive that American military officers would say only that it was somewhere in southwest Asia.

Trump has visited Al Udeid

Trump visited the air base during a trip to the region last month.

It was the first time a sitting US president had travelled to the installation in more than 20 years.

Al Udeid cleared its tarmacs

Last week, ahead of the US strikes on Iranian nuclear facilities, Al Udeid saw many of the transport planes, fighter jets and drones typically on its tarmac dispersed. In a June 18 satellite photo taken by Planet Labs PBC and analysed by The Associated Press, the air base's tarmac had emptied.

The US military has not acknowledged the change, which came after ships off the US Navy's 5th Fleet base in Bahrain also had dispersed. That's typically a military strategy to ensure your fighting ships and planes aren't destroyed in case of an attack.