(Updates with opening statements)
By Lisa Maria Garza
FORT HOOD, Texas, Aug 6 (Reuters) - Accused Fort Hood shooter Nidal Hasan said on Tuesday that war is an ugly thing with death and devastation on both sides, in a brief opening statement at his long-awaited trial for killing 13 U.S. soldiers in 2009.
Hasan is representing himself at the trial on the Texas Army base where he opened fire just days before he was to be deployed to Afghanistan, killing 13 people and wounding 32.
Hasan, 42, an American-born Muslim, has said he shot the soldiers to try to stop what he has called a U.S. war on the Muslim religion.
"Witnesses will testify that war is an ugly thing. Death, destruction and devastation are felt from both sides, from friend and foe. Evidence from this trial will only show one side. I was on the wrong side but I switched sides," Hasan said in a statement that lasted only about two minutes.
An Army psychiatrist at Fort Hood at the time of the shooting, Hasan has since apologized for being in the U.S. military and helping the American effort after the Sept. 11 attacks. He has tried to renounce his U.S. citizenship.
Prosecutors took about an hour to lay out their case against Hasan, saying that he intended to kill indiscriminately.
"Evidence will show that Hasan didn't want to deploy (to Afghanistan) and he possessed a jihad duty to kill as many soldiers as possible," lead military prosecutor Colonel Michael Mulligan said.
Hasan could be sentenced to death if convicted.
The military judge for the court-martial, Colonel Tara Osborn, ruled on Friday that prosecutors may present evidence that Hasan was on the Internet in the days, and even hours, before the attack, searching terms such as "Taliban" and "jihad," which some radical Islamists define as a holy war.
Hasan has said he plans to call only two witnesses at trial, according to Fort Hood officials. The witnesses were not identified.
Hasan may cross-examine any witness, including survivors of the attack. Hasan was shot by base police to end the Nov. 5, 2009 rampage. He was paralyzed from the chest down and is confined to a wheelchair.
Hasan faces 13 charges of premeditated murder and 32 charges of attempted premeditated murder. The dead included 12 active duty soldiers and a retired chief warrant officer who worked as a civilian employee at the base.
The jury of 13 Army officers includes nine colonels, three lieutenant colonels and a major.
The trial had been delayed repeatedly over procedural issues, such as whether he would be allowed to keep a beard that violates military grooming regulations, which he has said he wears for religious reasons.
Hasan had sought to use a "defense of others" strategy at trial, arguing that his actions were taken to protect Muslims and the Taliban in Afghanistan from U.S. assaults. Osborn denied that request.
Osborn rejected Hasan's offer to plead guilty in return for being spared the death penalty. A unanimous verdict of guilty is required for execution to be an option. The last execution carried out by the U.S. military was in 1961. (Writing by Greg McCune; Editing by Claudia Parsons)