Iran-linked drone strike that killed US troops highlights military vulnerability overseas

President Joe Biden's vow to swiftly respond to the weekend's drone attack that killed three U.S. troops and injured 34 others highlights more than just the harsh reality that violence has spread across the Middle East amid the war in Gaza.

It also spotlights the risks faced by the more than 40,000 U.S. troops deployed at multiple Middle East locations, as well as in many more parts of the world than Americans may know about.

Biden accused "radical Iran-backed militants" in Iraq and Syria for Saturday's attack on Tower 22, a U.S. military outpost in Jordan near the border with Syria. The Islamic Resistance in Iraq claimed responsibility. The group is a loose coalition of militias supported by Iran who oppose U.S. support for Israel in the war in Gaza and American involvement in the region more broadly. Iran denies any involvement in the weekend drone attack on U.S. troops.

They were not the first U.S. military deaths in the region since Hamas' Oct. 7 attack on Israel. Two U.S. Navy Seals went missing and are presumed dead following an operation on Jan. 11 when they boarded a ship off the coast of Somalia suspected of delivering Iranian weapons to Houthi rebels in Yemen.

What are some other incidents involving US troops since Oct. 7?

Iran-aligned militias have attacked U.S. troops with rockets, missiles and drones more than 150 times since the start of the Israel-Hamas war, according to the Pentagon. While Saturday's fatal incident marked the first time U.S. troops have been killed in one of these attacks, others have come pretty close.

To cite just a few:

On Oct. 18, U.S. forces in Iraq were targeted in two separate drone attacks. One of the drones was intercepted but still exploded, causing minor injuries. A day later, U.S. forces in Syria suffered minor injuries in another drone attack. Later that same month, a drone penetrated U.S. air defenses and crashed into a barracks in Iraq housing American troops, but failed to detonate. One U.S. service member suffered a concussion.

On Christmas Day last year, one U.S. service member was left in a critical condition and two more were wounded in a drone attack in Iraq. On Jan. 20, four U.S. soldiers suffered traumatic brain injuries after Iran-backed militias fired multiple powerful ballistic missiles and rockets at an air base in Iraq.

US retaliates: Warplanes strike Iranian-backed militias that wounded four American troops

Where are US troops stationed in the Middle East?

About 2,500 U.S. troops are based in Iraq and 900 in Syria. The Pentagon says they are there to prevent a resurgence of the Islamic State group − to act as a deterrent. Iraq wants the troops on its soil to leave because it views them as destabilizing for the country and region, though it has not set a deadline.

U.S. critics such as Benjamin H. Friedman, policy director of the Washington, D.C.-based Defense Priorities think tank, say the soldiers who were killed and wounded should not have been there in the first place.

"The militia that killed U.S. forces should be held accountable. But we should ask why U.S. forces in the area were left in range of repeated drone, missile, and rocket attacks. What cause justified this predictable danger? The answer is none. The U.S. government put them in harm’s way in service of a murky and pointless mission."

Following Hamas' attack on Israel, the Pentagon scrambled two aircraft carrier groups, with approximately 7,500 military personnel aboard each, to the Middle East. U.S. Defense Secretary Lloyd Austin ordered 2,000 troops to be ready to deploy to the region, though they are not likely to serve in combat roles.

Thousands of U.S. troops are stationed in Bahrain (9,000), Kuwait (13,000) and Qatar (8,000), along with a few thousand each in Jordan, Saudi Arabia and the United Arab Emirates. The Pentagon does not consistently release precise totals and most figures are estimates based on media releases and White House statements.

There are reports the U.S. maintains a classified military base in Israel's Negev desert code-named "Site 512." If true, it could be as close as 20 miles from Gaza. It's thought to be a radar site for monitoring missile activity.

Far-flung: Where else are US troops located overseas?

As of 2022, about 220,000 U.S. military and civilian personnel were serving in more than 150 countries, according to the U.S. Defense Department. And there are up to 800 U.S. military bases overseas, according to data from the Pentagon and David Vine, an anthropologist and expert on the U.S. military at American University.

The vast majority of U.S. military personnel overseas are not engaged in fighting.

In Germany, about 45,000 Americans go to work each day around the Kaiserslautern Military Community, a network of U.S. Army and Air Force bases that accommodates schools, housing complexes, dental clinics, hospitals, community centers, sports clubs, food courts, military police and retail stores.

Exclusive: Maps show U.S. counterterrorism efforts across globe, spanning 78 countries

About 60,000 American military and civilian personnel are stationed in Japan and another 30,000 in South Korea. More than 6,000 U.S. military personnel are spread across Africa, according to the Defense Department.

Still, more than nearly a quarter-century after the U.S. launched its response to 9/11, the Pentagon continues to pursue military actions in the Middle East and in many more parts of the world than Americans may realize, according to data from research by the Costs of War project at Brown University's Watson Institute.

From 2021 to 2023 − the first three years of the Biden administration − the U.S. military carried out counterterrorism operations in 78 countries. These globe-spanning operations saw U.S. troops engaged in direct combat, launching drone attacks, patrolling borders, gathering intelligence and training other nations' militaries.

"It makes U.S. forces vulnerable to attack and increases the likelihood of the U.S. engaging in a much bigger offensive war," Brown researcher Stephanie Savell previously told USA TODAY.

This article originally appeared on USA TODAY: US troops killed in drone attack in Jordan highlights vulnerability