The Pentagon is considering big changes to how it positions US forces in Europe and the Middle East, in what could amount to a major military shake-up.
President Donald Trump's administration made it clear in this year's National Defence Strategy that it wants allies to do more in Europe and the Middle East so the US can focus on China and the Western Hemisphere, where Washington is increasingly targeting drug cartels in South America.
In the Gulf, the war in Iran has underscored how vulnerable troops posted to the region can be. At least 18 US service members have been killed, including six in an Iranian missile strike at Port Shuaiba in Kuwait.
"Iranian strikes damaged and destroyed hundreds of buildings and structures at US bases in Kuwait, Bahrain, Qatar, UAE, Saudi Arabia, Iraq, Oman and Jordan," an inspector general's report into the costs of the war found.
The report, released this week, also said Pentagon officials have yet to decide whether they will return base and troop levels to what they were before the war.
The Pentagon "has not determined what its future posture will be in the region, how it will construct its bases, and what percentage of the construction costs allies partners will contribute", the report states.
The Washington Post has reported that the Pentagon is looking at whether it will move troops away from the Gulf. Typically, about 40,000 US personnel are based across the region.
An official told the Post that Defence Secretary Pete Hegseth had not yet ordered a formal review of force posture in the Middle East.
CNN on Friday reported that the Pentagon is expected to send MQ-9 Reaper drones currently operating in Africa to be used in South America as the US increases its anti-narcotics operations.
Mr Hegseth in June announced a six-month review for Europe that is looking at the US troop presence there. The effort is led by Elbridge Colby, undersecretary of defence for policy, who has long advocated greater focus on deterring China.
Among the possibilities being considered by Pentagon officials, Reuters reported on Thursday, is withdrawing about 25,000 troops from Europe, a move that would worry European and Nato officials who are facing an increasingly confrontational Russia. The US currently has about 80,000 troops in Europe.
While reducing force levels in Europe or the Middle East could free up resources for other priorities, it also raises questions about US deterrence in both regions and the reliability of Washington's commitments.
Senator Jeanne Shaheen, the senior Democrat on the Senate foreign relations committee, on Thursday asked Secretary of State Marco Rubio to ensure that US diplomats are involved in the Pentagon-led review of America's military presence in Europe.
In a letter addressed to Mr Rubio, who is also National Security Adviser, Ms Shaheen said that diplomats, including US ambassadors, are being kept out of the loop.
"The Department of State, which is responsible for managing our bilateral relationships, has traditionally played a substantial role in reviews of this kind," she said in the letter.
"Yet what we are hearing through our own conversations, travel across Europe and engagement with our allies tells a different story. US ambassadors and chiefs of mission in affected countries have been excluded from consultations."
A State Department official disputed the issues raised in the letter, saying that diplomats were being consulted.
Ms Shaheen wrote that adjustments in troop levels would have an effect on bilateral relationships that the State Department would be left to manage, with the Baltic nations of Estonia, Lithuania and Latvia among the countries with the most at stake.
European leaders have warned of incidents, often attributed to Russia, that fall below the threshold of conventional military attacks but undermine European security – such as sabotage, arson and drone incursions.
