The Pentagon has officially identified a soldier killed in a drone attack in Kuwait on Sunday, during U.S. military operations against Iran, while another soldier is presumed dead from the same incident.

Army Reserve Major Jeffrey O’Brien, aged 45, lost his life in the attack by an unmanned aircraft system at Port Shuaiba, Kuwait, marking the second full day of conflict.

O’Brien hailed from Indianola, Iowa, and was a member of the 103rd Sustainment Command based in Des Moines, Iowa.

His death marks the fifth confirmed casualty among six soldiers who have died in the ongoing conflict with Iran.

The Department of Defense has also reported that another Army Reserve soldier is believed to have died in the attack.

Chief Warrant Officer Robert M. Marzan, part of the same unit as Major O’Brien, is presumed to have perished at the scene of the attack.

A medical examiner will confirm identification of the 54-year-old from Sacramento, California.  

The incidents are under investigation. The Pentagon directed The Daily Mail to the US Army Reserves when reached for comment.

The other soldiers identified Tuesday by the Pentagon were Capt. Cody A. Khork, 35, of Winter Haven, Florida; Sgt. 1st Class Noah L. Tietjens, 42, of Bellevue, Nebraska; Sgt. 1st Class Nicole M. Amor, 39, of White Bear Lake, Minnesota; and Spc. Declan J. Coady, 20, of West Des Moines, lowa.

Army Reserve Major Jeffrey O’Brien (pictured left), 45, died during an unmanned aircraft system attack at Port Shuaiba, Kuwait in the second full day of battle. Chief Warrant Officer Robert M Marzan, 54, was in the same unit as O’Brien and is suspected dead at the scene of the same attack

The Pentagon confirmed the identity of a soldier who died and another believed to be dead in a drone attack in Kuwait on Sunday during the US’ strikes on Iran 

O’Brien was promoted to major in August 2024, according to a Facebook post, which shows him alongside two young children. 

He served in the Army Reserve for nearly 15 years, according to his LinkedIn.

The signal officer and information systems engineer in the Army Reserve was a manager of defensive cyber operations at an Iowa-based cybersecurity company, according to his LinkedIn. 

He had a career spanning two decades in information and cybersecurity.

Iowa Governor Kim Reynolds released a statement Wednesday offering prayers and condolences for the families of the Iowa residents killed.

‘Our hearts are broken by the deaths of Major Jeffrey O’Brien and Sergeant Declan Coady, two brave Iowa soldiers who gave the ultimate sacrifice to secure freedom and peace,’ Reynolds said.

A source familiar with the tragedy told CNN that the makeshift command center was struck by a direct hit at the center of the building, which they described as a triple-wide trailer with office space inside, just after 9am local time. 

The attack came very quickly, with no warning or sirens to alert troops to evacuate or get into a bunker, the source added. 

Hours after the attack, the source said, fire was still smoldering in some parts of the building, with the walls blown outwards from the blast. 

The command center had concrete barriers surrounding it, which is typical for military structures overseas, but nothing that could shield it from drones or missiles, the source said.

Three officials also told CBS News that prior to the attack, there had been discussion on the ground about whether the tactical operations center in question should not have been used as it concentrated too many people in a location that was not easily defended. 

Defense Secretary Pete Hegseth, however, said on Monday that the strike hit a ‘tactical operation center that was fortified.’

He then claimed that there was just ‘one’ projectile that made it through the air defenses. 

The strike on the facility now remains under investigation. 

On Tuesday, the Pentagon identified the other four soldiers killed in a drone strike in Kuwait as Capt. Cody A. Khork, 35, of Winter Haven, Florida (left) and Sgt. 1st Class Nicole M. Amor, 39, of White Bear Lake, Minnesota 

Sgt. 1st Class Noah L. Tietjens, 42, of Bellevue, Nebraska, and Spc. Declan J. Coady, 20, of West Des Moines, lowa were also killed

In the meantime, President Donald Trump has vowed to ‘avenge’ the fallen soldiers, as he warned that others may die as the operation continues.

‘America will avenge their deaths and deliver the most punishing blow to the terrorists who have waged war against basically, civilization,’ he said from Mar-a-Lago on Sunday, hours after the blast.

Trump then called the three service members ‘true American patriots who have made the ultimate sacrifice for our nation, even as we continue the righteous mission for which they gave their lives.’ 

Speaking to reporters on Monday, Chairman of the Joint Chiefs of Staff Gen. Dan Caine also killed the service members killed in ‘Operation Epic Fury’ as ‘the best that our nation has to offer’ and ‘true examples of what selfless service means.’

‘Our deepest and heartfelt condolences are with the families, their friend and their units,’ he said. ‘We grieve with you and we will never forget you.’ 

The soldiers’ friends have since started to share their own memories of their loved ones, with a friend of Captain Khork’s taking to Facebook to share how he had been there for him ‘for over 16 years of my life and been part of every major life event I’ve had.

‘He has shaped me into the person that I am today,’ the friend wrote, adding that Khork ‘knows more about me than anyone else and he was the first person to answer my call, even when I called in the middle of the night.

‘He’s helped me get through the hardest and lowest parts of my life and been there to celebrate the best. 

‘I’ve watched him support others and myself through the years when he had nothing to his name and never complained about it. That’s just the type of person he was,’ the friend continued.

‘He went out doing what he loved, defending our freedom. RIP brother, Valhalla is waiting for you. We will see each other again.’