By Sarah Morris
BBC News in Washington
New rules covering the death penalty in military courts suggest the US army may be preparing for its first execution since 1961.
The rules technically allow executions at Guantanamo Bay
The new rules spell out the procedures for carrying out death sentences imposed at courts martial.
There are six men on death row, all held at Fort Leavenworth in Kansas.
Anti-death penalty campaigners fear the new move may pave the way for the execution of Pte Dwight Loving, who was convicted of killing two taxi drivers.
The drivers were killed while Loving was stationed at Fort Hood, Texas, in 1988.
The court of appeals for the armed forces rejected his latest appeal last month.
He now has few legal resources left at his disposal.
The execution would have to be approved by President George W Bush to go ahead.
Two other servicemen were sentenced to death last year.
Sgt Hassan Akbar was convicted of killing two officers in Kuwait in 2003.
A jury also sentenced Senior Airman Andrew Witt for stabbing to death another airman and his wife.
The new rules are acknowledged by senior ranks as a major revision of the existing situation.
The revision also makes it possible for executions to take place at any military prison, not just Fort Leavenworth.
This, according to anti-death penalty protesters, means it would be technically legal for executions to take place at Guantanamo Bay.
Currently 10 detainees there have been charged with various offences, but none of them are capital cases.