A Houthi threat to impose a naval blockade against Saudi Arabia in the Red Sea could significantly widen the Iran war and strain a US military already focused on stopping Tehran’s attacks across the region, current and former US officials said.
Yemen’s Iran-aligned Houthis said on Monday that they would not allow ships to load or unload at Saudi ports, potentially blocking Saudi oil exports and choking off an additional 7% of global oil supply.
Saudi Arabia, which hosts US forces, has not yet requested military assistance from Washington.
However, Trump suggested on Tuesday that a move by the group to obstruct shipping in the Red Sea – a vital corridor for global trade – could draw the United States in.
"If something like that happens, we’ll take care of it. We’ve done that with the Houthis before,” Trump told reporters on Tuesday.
For the US military, it may not be so simple.
The Houthis have earned a reputation as hardened, nimble fighters who have successfully resisted earlier Saudi and US bombing campaigns.
Taking them on would mean stretching American resources already focused on fighting Iran and maintaining the United States’ own blockade of Iranian ports in the Gulf.
"You’re bifurcating your admittedly fairly robust resources in the region between two active fronts,” said Jason Campbell, a former senior Pentagon official.
Campbell, now with the Middle East Institute, added that addressing the Red Sea threat could mean shifting US warships from the Gulf closer to Yemen to allow the military to carry out operations against the militants and defend against Houthi missiles.
The possible entry of the Houthis into the conflict is another example of how the war – first pitched by Trump as a focused bombing campaign that would trigger
Iran’s capitulation – continues to evolve, worsening a political headache for the US president.
And if US Navy vessels and aircraft have to start shooting down Houthi drones and missiles, it could also worsen what experts have warned are diminished stockpiles of US munitions and air defense interceptors.
The Pentagon said the US military has everything it needs to "execute at the time and place of the president’s choosing”.
"We have executed multiple successful operations across combatant commands while ensuring the US military possesses a deep arsenal of capabilities to protect our people and our interests,” Pentagon spokesman Sean Parnell said.
The Houthis have been remarkably resilient through years of bombing by a Saudi-led Arab coalition, which tried unsuccessfully to crush the mountain fighters who are the de facto authority over much of Yemen, and more recent intense US bombing campaigns.
"The Houthis have proven many times in the past that they have the ability and willingness to obstruct maritime traffic in the Red Sea and the Bab el-Mandeb strait,” said Michael Mulroy, a former deputy assistant secretary of defence for the Middle East during Trump’s first term.
Under Joe Biden’s administration, the United States conducted air strikes against Houthi targets in an effort to keep open the crucial Red Sea trading route.
Trump intensified that effort last year, bombing the Houthis who had been firing at US warships and commercial vessels off Yemen’s coast.
Experts believe neither campaign ended the group’s ability to threaten shipping.
However, last year’s two-month action did demand significant US firepower, including two aircraft carriers, other warships, fighter jets and strategic aircraft such as the B-2 bombers.
While the US military is the best funded in the world, it still faces resource constraints, officials say, with many of the systems likely needed for Yemen currently being used in the war in Iran.
"We’re pretty busy already,” one official said, noting that some warships had spent longer than usual at sea because of the high tempo of operations, first in the Caribbean and now in the Middle East.
Longer than expected deployments wear on service members. Ships eventually need to return to port for maintenance.
More than 20 US Navy warships and hundreds of US military aircraft are now operating in the Middle East.
Additional forces are headed to the region to help with the Iran conflict, a second US official said.
That could limit what is available for a conflict near Yemen, which officials say would require significant naval and aerial resources, and would divert US intelligence resources, given the need to pinpoint Houthi capabilities that may have changed since last year.
Mark Cancian, a retired US Marine officer at the Centre for Strategic and International Studies, agreed that a second front in the Red Sea would stretch US naval forces.
However, he added, the Houthis would face their own challenges getting resupplied, given the ongoing blockade of Iran, which has been the group’s main supporter.
"The US blockade is not 100% effective but it is highly effective. As a result, the Houthis may be hard pressed to continue a campaign for long,” Cancian said.