What could have possessed a U.S. Army psychiatrist to open fire on his fellow soldiers at Fort Hood? In the absence of an explanation from the accused, Nidal Malik Hasan, we simply don't know the answer. Sadly, many Americans steeped in the memory of the 2001 terror attacks will blindly assign blame for Hasan's murderous rampage to his religious beliefs.

President Barak Obama on Friday quickly warned "against jumping to conclusions until we have all the facts." And American Muslims rightly condemned Hasan's "cowardly" act as antithetical to the teachings of Islam. Just as it was unrepresentative of the Muslim community in the United States, and the approximately 3,000 Muslims who honorably serve in the U.S. military.

We share the concern of many that last week's awful tragedy in Texas will add to the suspicion and hostility that animate some Americans' perceptions of Arab Muslims, here and abroad. That, too, would be tragic, and unworthy of this polyglot nation of immigrants.

Yes, Hasan is a Muslim of Arab heritage who regularly worshipped at a mosque. True, he was known to engage in "anti-American rants." He was also heard to define the United States' war on terror as "a war on Islam." And he did, indeed, shout "Allahu akbar!" -- God is great -- when he began his attack that left 13 people dead and 29 others wounded .

Perhaps it is unnecessary, but we will nonetheless state the obvious: Not all Muslims are violent. Or murderous. Or anti-American. What is just as obvious, but worth mentioning, is that Hasan is one man, and his evil deed reflects on him alone.

Obvious or not, we must remember that. And we must make sure our children remember it, too.

What is not yet obvious, but of deep concern, is why Hasan's outspoken opposition to the wars in Iraq and Afghanistan, his anti-American views, and his bitter complaints about anti-Muslim bias in the military do not appear to have raised serious doubts among his superiors about his fitness for the military. Let alone his suitability for counseling returning soldiers suffering from post-combat stress.

Not only must military and civilian authorities determine what was known about Hasan, and by whom, but also how he was able to illegally bring loaded weapons into a facility crowded with unarmed soldiers.

And, perhaps most important, if anti-Muslim sentiment in the military merely mirrors that in our broader culture, what can each of us do to address it?