Iranian attacks on U.S. military installations in the Middle East and alleged threats against bases in Britain are forcing Washington and its allies to reassess the risks of hosting American forces, according to an Al Jazeera analysis published Thursday.

The facilities have long helped the United States fight distant wars while offering host countries protection. But analysts interviewed by Al Jazeera said the war on Iran has exposed vulnerabilities that can make those same installations targets for retaliation.

The U.S. withdrew all 12 of its B-1 Lancer bombers from RAF Fairford in Gloucestershire in October, Al Jazeera reported. British authorities accused Iran of involvement in a plot against the base, an allegation Tehran denied. Earlier this month, Washington also moved a dozen aircraft out of RAF Mildenhall. The nature of the reported threat there remains unclear.

The risks extend well beyond Britain. A September report by the Pentagon’s watchdog found that Iranian attacks damaged or destroyed hundreds of buildings and structures at U.S. military installations across eight Middle Eastern countries during the war’s first four months, according to Al Jazeera.

In Kuwait, an attack on the Port of Shuaiba killed six U.S. service members and destroyed an army operations centre. Other strikes damaged aviation, maintenance and refuelling facilities at Kuwaiti bases.

An Iranian strike also damaged the early-warning radar at Qatar’s Al Udeid airbase, which houses U.S. Central Command’s air operations headquarters. In Bahrain, a drone hit communications equipment at the U.S. Fifth Fleet headquarters.

Simon Mabon, a Lancaster University international politics professor, told Al Jazeera that the American security umbrella was becoming a “double-edged sword.” Bases can help defend host countries through missile interception and weapons transfers, while also exposing them to attacks connected to a war they did not choose to start.

Mark Hilborne, a defence studies lecturer at King’s College London, said drones and relatively inexpensive ballistic missiles have made large bases easier to target.

The strategic dilemma remains unresolved. Al Jazeera cited July reports that Washington had moved military assets from damaged Gulf bases to Jordan and was considering shifting assets to Israel. Analysts said dispersing forces could reduce some exposure, but would not remove Washington’s need for overseas facilities.

Sources