Iran on Sunday threatened military bases used by US forces to launch attacks on the country’s nuclear sites, saying such facilities would be considered legitimate targets.The United States has thousands of troops deployed on bases across the Middle East.The following countries have major concentrations of US forces in the Middle East, which fall under the US military’s Central Command (CentCom).BahrainThe tiny Gulf kingdom hosts an installation known as Naval Support Activity Bahrain, where the US Navy’s Fifth Fleet and US Naval Forces Central Command headquarters are based.Bahrain’s deep-water port can accommodate the largest US military vessels, such as aircraft carriers, and the US Navy has used the base in the country since 1948, when the facility was operated by Britain’s Royal Navy.Several US ships have their home port in Bahrain, including four anti-mine vessels and two logistical support ships. The US coastguard also has vessels in the country, including six fast response cutters.IraqThe United States has troops at various installations in Iraq, including Al-Asad and Arbil air bases. The Iraqi government is a close ally of Iran, but also a strategic partner of Tehran’s arch-foe the United States.