The soldier was sent with a Russian expedition to Akator to return a Crystal Skull. However their captives, Indiana Jones, Marion Ravenwood, and Mutt Williams escaped from their truck which initiated a chase for the artifact.
After Colonel Spalko was collected, the soldier and his comrades used ropes to climb down the side of a cliff when a vehicle hijacked by Ravenwood and her family drove over the cliff edge and landed in a tree growing out from the wall which lowered them into the river below. The tree snapped back and hit the descending Soviets, killing three men but the expedition continued their jouney to Akator.
When the soldier and his compatriots finally reached Akator, with the help of double agent George McHale, they recaptured Jones and his friends along with the skull upon their arrival, but when Spalko place the skull on the headless skeleton of an Interdimensional being, a portal opened in the chamber's ceiling and it pulled the soldier and all the other Soviets inside.
Behind the scenes
The unidentified Russian soldier was played by an uncredited performer in Indiana Jones and the Kingdom of the Crystal Skull. Like one of his comrades, this Soviet is one of the two uncredited soldiers who appear in the Temple of Akator sequence.
While he and his companions are sucked into the vortex in the film, the soldiers receive a different fate in the comic book adaptation. There they are incinerated by the piercing gaze of the crystal skeletons of the temple.