War on Iran: What troops is the US moving to the Gulf? 

Nearly four weeks into Operation Epic Fury, United States President Donald Trump has claimed that Washington is engaged in negotiations with Tehran – talks that Iran denies are happening – while amassing thousands of troops in the Middle East.

What began on February 28 as a joint US-Israeli air campaign targeting Iran’s military infrastructure has now, by the final week of March, expanded into the largest deployment of soldiers to the region since the Iraq War.

One strike group, affiliated with the aircraft carrier USS Abraham Lincoln, is operationally active in the combat zone as of now, with the carrier USS Gerald R Ford temporarily out of action for repairs in the Mediterranean.

The air campaign has struck more than 9,000 targets across Iran, including sites linked to former Supreme Leader Ayatollah Ali Khamenei, Islamic Revolutionary Guard Corps (IRGC) headquarters, ballistic missile facilities, drone production centres and naval assets, according to US Central Command (CENTCOM).

More than 140 Iranian vessels have been damaged or destroyed, US officials say. Iran has responded with near-daily missile and drone attacks targeting Israel, Gulf Arab states and US military bases, while effectively closing the Strait of Hormuz to most commercial shipping.

The narrow waterway, through which about 20 percent of the world’s traded oil passes each day, has become the central strategic pressure point of the conflict.

It is against this backdrop that Washington is now reinforcing its ground presence.

US President Trump made no secret of his intentions in the weeks before the first strikes.

“We have a big force going towards Iran,” he told reporters in late January. “We have a lot of ships going that direction. Just in case, we have a big flotilla going in that direction, and we’ll see what happens.”

After US warplanes struck Kharg Island earlier this month, Trump said in a Truth Social post that his forces had “obliterated” military targets there, warning that the island’s oil infrastructure could be next if Iran did not reopen the strait.

On Tuesday, the Pentagon ordered approximately 2,000 soldiers from the US Army’s 82nd Airborne Division to begin moving to the Middle East, according to US media reports.

The deployment adds to two Marine Expeditionary Units already en route from opposite sides of the Pacific. US Defence Secretary Pete Hegseth confirmed that CENTCOM had requested the reinforcements to expand operational options.

US Secretary of State Marco Rubio told a congressional briefing that the US may need to physically secure nuclear material inside Iran. “People are going to have to go and get it,” he said, without specifying who.

While no ground operation has been authorised yet, the convergence of US Marine amphibious forces, elite US Army paratroopers and a division-level command structure marks a significant expansion of US military options.

Three forces, one theatre

The reinforcements heading to the Gulf consist of three distinct formations, each with a different origin, route and timeline.

The first is the Tripoli Amphibious Ready Group, centred on the America-class assault ship USS Tripoli and the 31st Marine Expeditionary Unit (MEU).

Ordered out of Sasebo, Japan, on March 13, the group transited the Strait of Malacca and was at Diego Garcia in the British Indian Ocean Territory by March 23. It is expected to enter the CENTCOM area by late March or early April.

The second is the Boxer Amphibious Ready Group, built around the Wasp-class assault ship USS Boxer and the 11th MEU, based in Southern California in the US.

The group departed San Diego between March 19 and March 20. Covering approximately 22,200km (13,800 miles), it is not expected to reach the combat zone around mid-April at the earliest.

The third is a contingent of about 2,000 soldiers from the 82nd Airborne Division’s Immediate Response Force, based at Fort Bragg, North Carolina, which was the latest in line of US military reinforcements for the region.

Together, the two Marine groups would offer the US 4,500 Marines and sailors in the region. Combined with the 82nd Airborne contingent, nearly 7,000 additional troops have been deployed since the conflict began.

USS Tripoli and the 31st MEU

The USS Tripoli, an America-class amphibious assault ship, is the larger of the two Marine vessels heading to the Gulf.

Based in Sasebo alongside USS New Orleans, the group forms part of the US Navy’s forward-deployed presence in the western Pacific.

The 31st MEU, meanwhile, comprises about 2,200 Marines and sailors, built around a reinforced battalion with artillery, amphibious vehicles and specialised units.

At 261 metres (856 feet) long and weighing 45,000 tonnes, USS Tripoli can operate as a light aircraft carrier for F-35B jets while simultaneously deploying Marines by air and sea.

The 31st MEU is the Marine Corps’ only permanently forward-deployed expeditionary unit. It has previously taken part in Operation Desert Fox in 1998, patrolling off Kuwait during the Iraq weapons inspection crisis.

Operation Desert Fox was a four-day US and British bombing campaign against Iraq in December 1998, ordered by then-US President Bill Clinton and British Prime Minister Tony Blair.

USS Boxer and the 11th MEU

The second amphibious group is centred on USS Boxer, a Wasp-class assault ship based in San Diego, California.

The Boxer Amphibious Ready Group also includes USS Comstock and USS Portland, and carries the 11th MEU, based at Camp Pendleton, in California.

USS Boxer departed San Diego on March 19, and according to the US authorities, the deployment was accelerated by approximately three weeks from its originally scheduled date.

At a distance of approximately 22,200km (13,800 miles) from the Gulf of Oman, the group is at least three weeks from the theatre and is not expected before mid-April.

Like USS Tripoli, USS Boxer can deploy F-35B aircraft along with helicopters and other support platforms.

The 11th MEU includes about 2,200 Marines and sailors, alongside roughly 2,000 additional sailors across the three ships.

The unit has an extensive combat record in the Gulf. In 1990–91, it formed part of an amphibious deception plan that tied down Iraqi forces along the Kuwaiti coast.

That campaign followed Iraq’s invasion of Kuwait and involved a coalition of more than 700,000 troops from 35 countries.

In August 2004, the 11th MEU led operations in Iraq’s Najaf province and remained there until February 2005.

82nd Airborne Division

The 82nd Airborne Division, based at Fort Bragg, serves as the core of the US Army’s XVIII Airborne Corps.

Approximately 2,000 troops from its Immediate Response Force have now been ordered to the Middle East.

This brigade-sized formation of about 3,000 soldiers can deploy anywhere in the world within 18 hours.

The 82nd is the Army’s primary forced-entry unit, trained to conduct parachute assaults, seize airfields and secure terrain for follow-on forces. However, it deploys without heavy armour in the initial phase, limiting its ability to hold territory against counterattacks.

The division has a long combat history, including operations in Normandy and the Netherlands during World War II.

More recently, it has been deployed to the Gulf War in 1991, Afghanistan in 2001 and Iraq in 2003. It was also mobilised to the Middle East in January 2020 following the US killing of Qassem Soleimani, a senior IRGC commander.

What could these forces do?

The build-up has focused attention on a narrow set of potential missions rather than any sort of ground campaign, experts say.

Ruben Stewart, senior fellow for land warfare at the International Institute for Strategic Studies (IISS), told Al Jazeera that a ground campaign is not likely at this point.

The 2003 invasion of Iraq required around 160,000 troops for a country that is a quarter the size of Iran, he noted, while the combat force currently deploying, not including supporting troops, consists of two battalions of US Marines and two battalions of paratroopers, each of which are about 800 in number – a total of around 3,600.

“The force being deployed is consistent with discrete, time-limited operations, not a sustained ground campaign. Both are rapid-response, modular forces designed for raids, seizures of key terrain, and short-duration missions with limited follow-on presence,” Stewart said.

He also noted: “What is notably absent are the heavy armoured units, logistics depth, and command structures required for a prolonged land war. In practical terms, this is a force that can act quickly and selectively, but not one that could sustain operations deep inside Iran or over an extended period.”

While no ground operation has been ordered, the scale and composition of forces, combined with public statements from US officials, suggest at least three scenarios may be under consideration.

These include seizing or blockading Kharg Island, clearing Iran’s coastline to reopen the Strait of Hormuz, and, in the most consequential scenario, securing Iran’s nuclear material.

Kharg Island, a five-mile (8km) coral outcrop approximately 26km (16 miles) off Iran’s southwestern coast, handles an estimated 90 percent of Iran’s oil exports. US air strikes earlier this month damaged military infrastructure there, including its airfield.

Beyond Kharg, US Marine forces could carry out helicopter-borne raids against Iranian missile sites, mine stockpiles and fast-attack craft along the Strait of Hormuz.

Of the three options, securing the Strait of Hormuz is the most realistic operational scenario, Stewart said.

This would likely take the form of “limited action along the Strait of Hormuz such as securing key maritime terrain or suppressing threats to shipping. That aligns with the capabilities of amphibious and airborne forces operating from sea and regional bases,” he said.

Seizing Kharg Island is technically feasible but more escalatory, he added, given its centrality to Iran’s oil exports. “By contrast, securing Iran’s nuclear material would be the least realistic with this force as it would require a far larger, sustained ground presence,” Stewart said.

Overall, “the highest escalation risk comes from strikes on strategic infrastructure like Kharg Island or nuclear sites, which would likely trigger a broader Iranian response,” he said. “More broadly, as additional US forces are drawn into the Middle East, there is a risk that other actors exploit reduced US presence or attention elsewhere, so escalation dynamics need to be assessed globally, not just within the immediate theatre.”

Rubio’s remarks about securing nuclear material have also raised the prospect of operations targeting Iran’s key facilities, including Natanz, Fordow, and the Isfahan Nuclear Technology Centre. These sites have already been struck from the air.

Retired Admiral James Stavridis, former NATO supreme allied commander, warned in a recent Bloomberg opinion piece that any assault on Kharg Island would face “massive drone attacks, small boats loaded with explosives, and missiles” during transit through the strait.

He added that Iranian forces on the island could be “easily overcome by the first waves of US forces”, but cautioned that it could be heavily booby-trapped.

Diplomacy alongside escalation

The military build-up is unfolding alongside a fragmented and uncertain diplomatic effort and is best understood as “coercive leverage rather than a decision for war”, Stewart said.

“By moving forces into theatre, the US is increasing its bargaining power, signalling that it has options if diplomacy fails.”

Stewart warned, however, that this is a delicate balancing act. “As force levels grow, particularly if they expand beyond rapid-response units into heavier, sustained formations, the political and operational momentum becomes harder to reverse. At present, the deployment remains below that threshold, but continued build-up would increase the risk of inadvertent escalation or reduced diplomatic flexibility.”

On March 24, Trump said the US and Iran had reached 15 points of agreement in talks aimed at ending the conflict, describing discussions as “very, very strong”.

Iran, however, has denied any direct negotiations. Foreign Ministry spokesman Esmaeil Baghaei said Tehran had received messages from “certain friendly states conveying the US request for negotiations to end the war”, adding that “appropriate responses were given.”

Last weekend, Trump issued a 48-hour ultimatum for Iran to reopen the Strait of Hormuz or face strikes on its power plants. Hours before the deadline expired, he announced a five-day extension, citing “productive” conversations.

At the centre of emerging diplomatic efforts is Pakistan, which has moved to position itself as a potential intermediary.

Pakistan’s army chief, Field Marshal Asim Munir, spoke to Trump on Sunday, while Prime Minister Shehbaz Sharif held talks with Iranian President Masoud Pezeshkian on Monday, stressing the need for de-escalation.

Sharif later made the offer public in a post on X on March 24, tagging Trump, US envoy Steve Witkoff and Iranian Foreign Minister Abbas Araghchi.

“Subject to concurrence by the US and Iran, Pakistan stands ready and honoured to be the host to facilitate meaningful and conclusive talks for a comprehensive settlement of the ongoing conflict,” he wrote.

Trump reposted Sharif’s statement on Truth Social hours later.