Below, AFP examines the significant concentrations of US forces in the region -- which fall under the US military's Central Command (CENTCOM) -- and the various attacks Iran has reportedly carried out.

- Bahrain -

The 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 anti-mine vessels and logistical support ships.

Bahrain said that 5th Fleet's service center was targeted by an Iranian missile strike on Saturday.

- Iraq -

The United States has troops in Iraq's autonomous Kurdish region as part of the international coalition against the Islamic State group, but their mission is due to end by September under a deal between Washington and Baghdad.

American forces have already completed their withdrawal from facilities in federal Iraq -- whose government is a close ally of Iran, but also a strategic partner of Washington -- under the same agreement.

AFP journalists reported explosions near the US consulate in Arbil -- the capital of Iraqi Kurdistan -- on Saturday, while Iraq's powerful pro-Iran Kataeb Hezbollah group threatened attacks on American bases.

Kurdish security forces later said the US-led coalition had intercepted multiple drones and missiles over Arbil.

- Jordan -

The United States reportedly deployed dozens of military aircraft to Jordan's Muwaffaq Salti Air Base in the runup to the strikes on Iran.

A Jordanian military official said the kingdom's forces shot down two ballistic missiles targeting its territory on Saturday, without saying who launched them.

The Jordanian Public Security Directorate later said there were "no casualties but only material damage."

- Kuwait -

Kuwait has several US bases, including Camp Arifjan, the location of the forward headquarters for the US Army component of CENTCOM. The US Army also has stocks of equipment and supplies in the country.

Ali al-Salem Air Base hosts the 386th Air Expeditionary Wing, which the military describes as the "primary airlift hub and gateway for delivering combat power to joint and coalition forces" in the region. Additionally, the United States has deployed drones including MQ-9 Reapers to Kuwait.

Kuwait's defense ministry said its forces intercepted missiles targeting the air base on Saturday, while Italy's foreign minister said an Iranian attack caused "significant damage" to the runway of the facility, which also hosts Italian air force personnel.

- Qatar -

Al Udeid Air Base in Qatar includes the forward components of CENTCOM, as well the command's air forces and special operations forces.

It also hosts rotating combat aircraft, and the 379th Air Expeditionary Wing, which the military says includes "airlift, aerial refueling intelligence, surveillance, and reconnaissance, and aeromedical evacuation assets."

Iran fired missiles at Al Udeid last June following US strikes targeting Iranian nuclear facilities, and the Gulf emirate said an Iranian missile attack targeted its territory on Saturday.

- Syria -

The United States for years maintained troops in Syria as part of international efforts against the Islamic State group, which rose out of the country's civil war to overrun large parts of that country and neighboring Iraq.

US forces are currently in the process of withdrawing from Syria, and three sources told AFP earlier this week that the American exit would be completed within a month.

Syrian state media said four people were killed by an Iranian missile that hit the country's south on Saturday.

- United Arab Emirates -

Al Dhafra Air Base in the United Arab Emirates hosts the US 380th Air Expeditionary Wing, a force that is composed of 10 squadrons of aircraft and also includes drones such as MQ-9 Reapers.

Combat aircraft have rotated through Al Dhafra, which also hosts the US Air Forces' hub for "advanced air warfare training."

The UAE said it had intercepted two rounds of Iranian missile attacks on Saturday, with debris from the first wave killing a civilian in Abu Dhabi.