Maj. Nadal Malik Hasan, a U.S.-born citizen of Palestinian descent, is the sole suspect in the shootings.
Appearing on CNN’s State of the Union, Casey told CNN Chief National Correspondent John King “there’s an ongoing investigation and I can’t speak to the particulars of the investigation or to any motivation of Maj. Hasan.”
Echoing recent comments by President Obama and Texas’ Republican senators, Casey cautioned against speculating about the causes behind the shootings.
“We have to be careful,” Casey told King, “because we can’t jump to conclusions now based on little snippets of information that have come out.”
Casey said he was “concerned that this increased speculation could cause a backlash against some of our Muslim soldiers” and added that he had asked leaders in his service to be on the lookout for signs of a backlash.
“As great a tragedy as this was, it would be a shame if our diversity became a casualty as well,” the Army Chief of Staff also said Sunday.
Casey was quick to add that he does not think there is currently discrimination against the roughly 3,000 Muslims who serve in the Army as active duty soldiers or in the reserves.
Updated: 11:41 a.m.