U.S. soldier enters no plea in 2009 Iraq shootings TACOMA, Washington (Reuters) - A U.S. soldier accused of killing five fellow servicemen at a military combat stress center in Baghdad in 2009 entered no plea at an arraignment on Monday at a military base in Washington state. Sergeant John Russell, 48, is accused of going on a shooting spree at Camp Liberty, near the Baghdad airport, in an assault the military said at the time could have been triggered by combat stress. Russell, of the 54th Engineer Battalion based in Bamberg, Germany, faces five charges of premeditated murder, one charge of aggravated assault and one charge of attempted murder in connection with the May 2009 shootings. Six months ago, he was ordered to stand trial in a military court that has the power to sentence him to death, if he is convicted. Russell, tall and broad-shouldered with a military crew-cut and glasses, was mostly silent during the 15-minute hearing, answering only "Yes, sir" and "No, sir" to the judge's questions. Russell's attorney, James Culp, waived hearing of the charges on Russell's behalf and entered no plea for him, which is common practice in military justice procedure. No date has been set for the court-martial, but both military prosecutors and defense attorneys indicated on Monday that it could begin in March. The arraignment, at Joint Base Lewis-McChord near Tacoma, Washington, comes at a sensitive time for the Army, which is in the process of deciding how to prosecute Staff Sergeant Robert Bales, a soldier accused of killing Afghan villagers in cold blood earlier this year. A two-week hearing at Lewis-McChord to establish if there is sufficient evidence to send Bales to a court-martial wrapped up last week after harrowing testimony from Afghan adults and children wounded in the attack. Bales' civilian defense lawyers have suggested he was suffering from post-traumatic stress disorder. On Monday, Russell's attorney outlined a defense based on his declining mental state. Russell suffered from depression, thoughts of suicide, anxiety and stress from multiple deployments, and suffered "at least one traumatic experience involving civilian casualties" and "mass grave sites" while serving in Bosnia and Kosovo during 1998 and 1999, Culp said in presenting arguments to the judge after the arraignment. Culp and military defense lawyers, through telephone testimony presented by forensic psychiatric experts, told the judge they planned to use a Magnetic Resonance Imaging test to prove that Russell had brain damage. Another defense witness testified that forensic hypnosis would be needed to unlock Russell's memories of the shootings on May 11, 2009. Government witness Dr. Ronald Schouten, a forensic psychiatrist at Boston's Massachusetts General Hospital, argued against the effectiveness of either. "If we're doing brain imaging now, it doesn't tell us what it was three years ago," Schouten said. Later, he added: "Hypnosis has long been recognized as invalid and prone to providing inaccurate information." Dr. Robert Sadoff of the University of Pennsylvania, one of the country's top experts in forensic psychiatry, is scheduled to testify as a defense witness on Tuesday. Writing by Bill Rigby; Editing by Paul Thomasch, Peter Cooney and Mohammad Zargham