The Army psychiatrist charged in the 2009 shooting rampage at Fort Hood will represent himself at his upcoming murder trial, meaning he will question the more than two dozen soldiers he is accused of wounding, a military judge ruled Monday.

Maj. Nidal Hasan’s attorneys will remain on the case but only if he asks for their help, the judge said. Hasan, 42, faces the death penalty or life in prison without parole if convicted of 13 counts of premeditated murder and 32 counts of attempted premeditated murder.

Announcing his strategy shortly after the judge’s ruling, Hasan said he will use a “defense of others” argument, although he did not elaborate.

Hasan, who was set to deploy to Afghanistan with some of the troops killed that day on the Texas Army post, will probably try to show that he was trying to defend Muslims against U.S. troops in a war that he believes is illegal and immoral, military law experts said. To prove a “defense of others” argument, a defendant must show that a threat was imminent.

Hasan also asked for a three-month delay to prepare. The judge said she would decide that issue Tuesday, a day before jury selection is scheduled to begin.

Nidal Hasan, charged with killing 13 people and wounding 31 in a November 2009 shooting spree at Fort Hood, Texas, is pictured in an undated Bell County Sheriff's Office photograph. (HANDOUT/Reuters)

“Even if he feels the U.S. is in an unjustified war, this defendant is not going to be able to show a threat was immediate, because these soldiers were on U.S. soil and unarmed,” said Jeff Addicott, director of the Center for Terrorism Law at St. Mary’s University in San Antonio, who is not involved in Hasan’s case.

After questioning Hasan for about an hour, the judge, Col. Tara Osborn, ruled that Hasan was mentally competent to represent himself and understands “the disadvantage of self-representation.” She repeatedly urged him to reconsider his request, noting that the lead prosecutor has more than 20 years of experience and that Hasan will be held to the same standards as all attorneys regarding courtroom rules and military law.

“You’ve made that quite clear,” Hasan said after the judge asked whether he understood that representing himself was not “a good idea.”

At Osborn’s request, a doctor testified Monday about Hasan’s physical condition. Hasan was paralyzed from the waist down after being shot by police responding to the attack on Nov. 5, 2009.

The doctor said Hasan’s paralysis will not have a significant impact during proceedings but that Hasan can sit for only four consecutive hours and is limited in his ability to write.

At a hearing in May, Hasan told Osborn that he wanted to plead guilty. But Army rules prohibit a judge from accepting a guilty plea to charges that could result in a death sentence.