A senior defense official says the U.S. soldier accused in the killings of 16 Afghan civilians is expected to be flown to the U.S. military prison at Fort Leavenworth, Kan., as early as Friday.

The official, who spoke on condition of anonymity because of security surrounding the move, says the shift does not necessarily mean a decision was imminent on announcing formal criminal charges against the suspect.

The suspect, whose name has not been made public, was moved from Afghanistan to Kuwait on Wednesday. Officials say that transfer was necessary because there was no appropriate detention facility to hold him in Afghanistan.

Leavenworth is the military’s only maximum-security prison.