The three other soldiers were found dead on Monday after rescuers recovered their armoured vehicle from a swamp.

Lithuanian authorities received a report last Tuesday that the soldiers went missing during a military drill at a training ground in the eastern city of Pabrade, near the border with Belarus.

"The fourth US Army Soldier assigned to 1st Armored Brigade Combat Team, 3rd Infantry Division was found deceased near Pabrade, Lithuania the afternoon of April 1," US Army Europe and Africa's public affairs office said in a statement.

"The Soldier's identity is being withheld pending confirmation of notification of next of kin," it added.

The army did not specify where exactly the soldier was found.

Lithuania's defence ministry expressed "deep sorrow" over the death.

"We extend our condolences to the families of all four soldiers lost in this tragic accident and thank all those involved in the search efforts," it added on social network X.

US Defense Secretary Pete Hegseth thanked the "brave servicemembers who enabled this difficult recovery and to our Lithuanian hosts who labored alongside them".

"The recovery was conducted with urgency, resolve and deep respect for the fallen," he said on X.

"We will never forget these soldiers -- and our prayers are with their families."

Lithuania, a NATO and EU member, hosts more than 1,000 American troops stationed on a rotational basis.