The United States and Iran are set for talks this weekend in Oman as President Donald Trump reiterated this week threats of military action against Tehran if it does not agree to limits on its nuclear program.
Western countries suspect Iran is pursuing nuclear weapons, which Iran denies. If Iran does not make a deal, Trump has said, "There will be bombing, and it will be bombing the likes of which they have never seen before."
Here is what we know about the US military presence in the Middle East:
Where are US bases in the Middle East? The US has operated bases around the Middle East for decades and the largest is Al Udeid Air Base in Qatar, built in 1996, based on the number of personnel.
Other countries where the US has troops include Bahrain, Kuwait, Saudi Arabia and the United Arab Emirates.
There are normally about 30,000 US troops across the region, down sharply from when US forces were involved in major operations. There were more than 100,000 US troops in Afghanistan in 2011 and over 160,000 in Iraq in 2007.
The US has roughly 2,000 troops in Syria at small bases mostly in the northeast. About 2,500 US personnel are stationed in Iraq including at the US Union III site in Baghdad.
What reinforcements has Trump sent?
The Pentagon has said that it surged additional forces to the Middle East in recent weeks.
It also relocated as many as six B-2 bombers in March to a US-British military base on the Indian Ocean island of Diego Garcia, which experts said would put them in an ideal position to intervene quickly in the Middle East.
US Defense Secretary Pete Hegseth has said that it was up to Iran to decide whether to interpret this as a message to Tehran.
The Pentagon has also sent other aircraft and more air defense assets including a Patriot missile defense battalion.
Two US aircraft carrier ships are in the Middle East, and each carries thousands of troops and dozens of aircraft.
Why are US troops stationed in the region?
US troops are stationed in the Middle East for a variety of reasons.
In some countries like Iraq, US troops are fighting Islamic State militants and local forces. But over the past several years Iran-backed fighters have attacked US personnel who have struck back.
Jordan, a key US ally in the region, has hundreds of US trainers and they hold extensive exercises throughout the year.
US troops are in other countries such as Qatar and the UAE as a security assurance, for training and to assist in regional military action as needed.
The United States is undertaking a bombing campaign against Iran-backed Houthi forces in Yemen.
Do US bases in the region get attacked often?
US bases are highly guarded facilities, including air defense systems to protect against missiles or drones. Facilities in countries like Qatar, Bahrain, Saudi Arabia, Kuwait are not usually attacked.
But US troops in Iraq and Syria have come under frequent attack in recent years.
Since 2023, the Houthi movement has launched more than 100 attacks on ships off Yemen's coast, which they say were in solidarity with Palestinians over Israel's war in Gaza with Iran-backed Hamas militants.
These include drone and missile strikes on US Navy ships in the region. So far, no Houthi attack is known to have damaged a US warship.