Repeated attacks on American troops in the Middle East risk drawing the United States into a conflict with Iran even as Washington strives to prevent fighting between Israel and Hamas from spiraling into a regional war.
The United States has blamed the spike in rocket and drone attacks -- at least 14 in Iraq and nine in Syria since October 17 -- on Iran-backed forces, and carried out strikes last week in Syria on sites the Pentagon said were linked to Tehran.
Washington has massive firepower at its disposal but its military response to the attacks has so far been limited to those strikes -- which the Pentagon said did not appear to have caused casualties -- in a potential bid to head off a broader conflict.
"We are concerned about all elements of Iran's threat network increasing their attacks in a way that risks miscalculation, or tipping the region into war," a senior US defense official said Monday.
"Everybody loses in a regional war, which is why we're working through partners, with allies, working the phone lines, increasing posture to make clear our desire to prevent regional conflict," the official said.
Washington says the attacks on its troops are separate from the current Israel-Hamas conflict that began earlier this month when the militant group carried out a shock cross-border attack from Gaza that Israeli officials say killed more than 1,400 people.
But Iran said Monday that the attacks on US forces are the result of "wrong American policies" including support for Israel, whose retaliatory bombardment has killed more than 8,300 people, according to the Gaza health ministry.
There are roughly 2,500 American troops in Iraq and some 900 in Syria as part of efforts to prevent a resurgence of the Islamic State jihadist group, which once held significant territory in both countries.
The damage from the recent attacks on those forces has been limited so far -- 21 American personnel suffered minor injuries and a contractor died of a cardiac event while sheltering during a false alarm -- but there is significant potential for things to get worse.
"There is substantial risk for US-Iran escalation due to spillover from the Israel-Hamas war," either at Tehran's direction or because its proxies decide to on their own, said Jeffrey Martini, a senior defense researcher at RAND.
Iran has proxy forces in both Iraq and Syria that have repeatedly targeted American troops in the past -- something that had stopped prior to recent events due to Washington reaching "an informal understanding with Iran on reducing regional tensions," Martini said.
Jon Alterman, director of the Middle East Program at the Center for Strategic and International Studies, said the current situation differs from past spates of attacks because "all of Iran's proxies seem to be getting into the act simultaneously," increasing "the likelihood of something going wrong."
The United States has repeatedly said it wants to keep the Israel-Hamas war from becoming a broader conflict and has bolstered its forces in the region -- including with one carrier strike group that is there and another in transit -- as part of its deterrence efforts.
"Washington is seeking to hold back while simultaneously making clear that it doesn't need to," Alterman said of its response to the attacks on its troops, noting that deterrence "requires both the capability and willingness to inflict much more damage, while deciding not to do so."
"The challenge, from a US perspective, is if you never inflict that damage, your adversary doubts your willingness, but if you do inflict that damage, you can get trapped in an escalatory spiral."
