The US military on Monday confirmed that three of its soldiers were found dead in their armoured vehicle after it was pulled out of a swamp near the town of Pabradė in eastern Lithuania.
The three members of the 1st armoured brigade combat team, 3rd infantry division, have not been identified until the next of kin was notified, authorities said.
The fourth soldier from the same unit is still missing, with search and rescue efforts continuing.
This is what we know so far about the incident and the continued search for the last surviving US serviceman.
When did the soldiers go missing?
The four soldiers were first reported missing last Tuesday. The US Army was notified that they and their M88 Hercules vehicle had vanished in the sprawling "General Silvestras Žukauskas" training ground in eastern Lithuania.
The M88 Hercules, produced since 1961 in several variants and used in wars including Vietnam and Iraq, is a large armoured vehicle designed to retrieve tanks and other heavy equipment from the battlefield.
The 1st Brigade was conducting "gunnery tables" — a series of drills designed to evaluate a unit's ability to conduct a mission — when a Joint Light Tactical Vehicle aka Oshkosh become immobilised.
"The Hercules was dispatched to recover that vehicle," spokesperson for US Army Europe and Africa Major Nicholas "Nuke" Chopp told Euronews.
"Somewhere on their way to that vehicle, they encountered this body of water and entered it. We know nothing past that."
NATO Secretary-General Mark Rutte originally implied that the four soldiers were found dead, but the alliance then clarified his comments and confirmed the search was ongoing.
In response to the missing soldiers, the Lithuanian army and police launched a joint search operation with the US military.
Hundreds of rescuers searched through thick forests and swampy terrain around Pabradė, some 10 kilometres west of the border with Belarus.
How was the vehicle found?
After a three-day search, a US army member found the M88 Hercules the soldiers were travelling in submerged under at least 5 metres of water, clay-like mud and silt.
Hundreds of local and foreign troops and other rescue personnel, including Polish engineers and US Navy divers, were sent on site to recover the stuck vehicle.
Lithuanian divers were also on site rapidly, Chopp said. "Lithuania has been just unbelievable. It is literally an entire country that has pulled together to bring the soldiers home," he said, adding that the Baltic country's defence minister and prime minister came on-site to help support the rescue mission.
Once the Hercules was found, rescuers had to get through the mud to reach the vehicle first. "The divers weren't so much swimming as they were basically wrestling their way through it," Chopp said.
The M88 Hercules weighs approximately 70 tonnes, and entered the bog with momentum, Chopp explained. "Between the momentum and then gravity, it continued to be pulled down further into the mud."
Rescue efforts then focused on pulling the vehicle out. "I won't say we knew we were going to be able to, we weren't sure. At one point they estimated it was going to take approximately 600 tonnes of force to remove the Hercules from the bog," Chopp said.
Attempts faced a challenge again as two Hercules vehicles and additional Lithuanian bulldozers tried to pull the vehicle out of the swamp, with additional heavy dozers sent in to provide extra grip.
It was ultimately pulled out of the bog in the early hours of Monday morning after a two-hour effort, the US Army said, which is when three of the soldiers were found.
What happens next?
Lithuania's Defence Ministry said the country's police and US investigators were working on site to piece together what happened to the four soldiers.
The ministry said on X, "We will remain patient and focused as they gather more information about the situation."
Chopp says that rescue efforts have turned to finding the missing soldier. Lithuania has sent a military working dog team to the site, with Estonia joining the efforts.
The handler and the working dogs operate "in a rigid inflatable boat, what's frequently called a Zodiac," Chopp said. "They are moving around the bog in a grid pattern to see if the dogs can pick up any scent."
"The command's number one priority is continuing to search to recover our fourth soldier," Chopp said, adding that the incident has rattled the unit's tight-knit community.
An investigation has been opened into what happened to the soldiers and how their vehicle managed to become trapped in the swamp.
The terrain in the training area is rugged and challenging. It's designed to be an environment you would fight in, Chopp says, adding that it isn't uncommon for army vehicles to get stuck.
"Sometimes the terrain wins, basically. What obviously is not common at all is this tragedy. This is, fortunately for our soldiers, this is very rare, but also obviously one time is far too many."
