"I can only ask them to do a little research," he said during a recent interview. "If they think it's OK to invade another country and kill innocent people, that's up to them, but we strongly disagree."
Watada said his son has always been a straight arrow. The Eagle Scout and near straight-A student, who studied business and graduated from Hawaii Pacific University in 2003, once reluctantly reported high school classmates who were stealing cafeteria funds even though he knew that would label him a snitch, his father said.
After Watada graduated and began seriously considering military service, his father tried to dissuade him. The elder Watada had lost a brother in the Korean War and told his son he didn't want to lose him too.
As terrorist threats dominated the news, however, Ehren told his father he felt he had to serve his country. He received his officer's commission in 2003, served a year in South Korea and was to deploy to Iraq in June with his Stryker brigade combat team until he began researching the war and developing doubts.
Watada said his son offered to resign or deploy to Afghanistan but was rebuffed.
University of Illinois professor Francis Boyle, an international law expert who testified on behalf of Watada at an Army hearing this year, argued that the soldier was correct to believe the United States illegally launched the Iraq war because it failed to obtain authorization for it from the United Nations Security Council, as required under international law.
Boyle has also argued that the second required authorization -- a congressional war resolution -- was obtained under false pretenses because the Bush administration erroneously asserted that Iraq possessed weapons of mass destruction and was linked to Al Qaeda. The Nuremberg principles adopted after World War II require soldiers to disobey illegal orders, Boyle said.
But Army spokesman Col. Dan Baggio said political questions over a war's legitimacy were "not the kind of decisions lieutenants and captains make." He said soldiers had a moral obligation to refuse illegal orders in the field -- to shoot prisoners of war or innocent civilians, for instance -- but they could not pick and choose where to deploy.
"If your nation has made a decision, as a member of the military forces you have an obligation to go," Baggio said. "To me, that's black-and-white. I would be ashamed if I didn't fulfill the obligation and duty to those troops I serve and the oath I took."
As Ehren's doubts about the war grew, his father, who once tried to dissuade him from enlisting, was now trying to talk him into deploying. Just go, he told him. Keep your head low.
Watada said he couldn't bear to think of his son locked up for years in the military brig, his once promising career in tatters. But Ehren was adamant about his stand. "How can I lead my men in harm's way for no good reason?" he asked. "Didn't you always tell me to do the right thing?"
Watada had to say yes.
Today, he is his son's biggest booster, tirelessly giving speeches in the hopes that broad public support will help minimize Ehren's sentence. Lt. Gen. James M. Dubik, the Ft. Lewis commander, is expected to decide this month how to proceed in Watada's case.