VILNIUS -- The body of a fourth US soldier has been recovered at the Pabrade training ground in Lithuania's Svencionys district, the Baltic News Service (BNS) on Tuesday quoted US Army Europe and Africa as saying.

The discovery followed a seven-day search operation, during which a joint allied team worked day and night to locate the four missing soldiers and an armed vehicle they were riding.

The US Army has launched an investigation into the cause of the incident.

Lithuanian President Gitanas Nauseda expressed condolences following the recovery of the fourth soldier's body, BNS reported.

On Monday, the bodies of three of the four missing soldiers were found in a swamp at the Pabrade training area after their M88 Hercules vehicle was pulled from the waterlogged terrain.

The search and recovery operation began on March 25 after they went missing during a training exercise in the General Silvestras Zukauskas Training Area in Pabrade.

The multinational rescue operation involved troops from Lithuania, the United States, and Poland.