Asked whether he thought the Army “dropped the ball” in not responding to warning signs that the major was increasingly radical, General Casey replied that he was encouraging soldiers to provide information to criminal investigators. But he added that the Army needs to be careful not to jump to conclusions based on early tidbits of information.

“The speculation could heighten the backlash,” he said on “This Week.” “What happened at Fort Hood is a tragedy and I believe it would be a greater tragedy if diversity became a casualty here.”

Sen. Lindsey Graham, a Republican of South Carolina, and Sen. Jack Reed, a Democrat of Rhode Island, took also pains on Sunday to say that Muslims have served honorably in the military and at risk to their lives.

“At the end of the day this is not about his religion  the fact that this man was a Muslim,” Senator Graham said on CBS’s “Face the Nation.”

Senator Graham and Ike Shelton, a Missouri Democrat who chairs the House Armed Services Committee, were asked why the Army would have assigned a psychiatrist who had a poor performance record at Walter Reed Hospital and ranted about America’s war on terrorism to Fort Hood. Mr. Skelton said he was briefed by the Army and was told it is investigating such assertions.

“Let’s give them a few days to find out just where the ball was dropped, if that’s the case” he said.

Senator Graham’s echoed his restraint.

“I mean does every soldier who shows discontent with the war and every soldier that has had a bad performance report  what are we going to do with those folks?” Sen. Graham said. “At the end of the day, maybe this is just about him. It’s certainly not about his religion, Islam.”