The U.S. government is concerned about a possible backlash against American Muslims stemming from the last week's shooting at Fort Hood.

Homeland Security Secretary Janet Napolitano said Sunday that her agency is working with groups around the United States to try to head off any backlash.

And the U.S. Army's top general said he is concerned about a backlash in the military against Muslim troops.

General George Casey, the U.S. Army's Chief of Staff, cautioned against jumping to conclusions about whether religious beliefs motivated the accused gunman, Major Nidal Malik Hasan, a Muslim born in the United States, of Palestinian immigrant parents.

"I'm concerned that this increased speculation could cause a backlash against some of our Muslim soldiers. And I've asked our Army leaders to be on the lookout for that," Casey told CNN's "State of the Union" Sunday.

Napolitano was in Abu Dhabi Sunday where she told reporters, "Obviously we object to – and do not believe – that anti-Muslim sentiment should emanate from this. This was an individual who does not, obviously, represent the Muslim faith."

She said her agency is working with state and local groups to try to head [off] any anti-Muslim anger.

But a backlash is already in motion, although so far it is visible mainly among commentators long known for their anti-Muslim bias. For example, Debbie Schulssel, who frequently attacks Islam and Muslims, wrote on her blog:

"He [Hasan] had every opportunity given to him by American taxpayers. And he murdered them anyway. This isn't just the Palestinian way. It's the Islamic way ... Think of Hasan ... whenever you hear about how Muslims serve their country in the U.S. military. Well, actually, they do serve 'their country' in the U.S. military. And their country is Dar Al-lslam and greater Koranistan. It's Islamic terrorism, stupid. Wait, that's repetitive. It's Islam, stupid."

Maj. Hasan's family says he confided in them that he felt harassed as a Muslim in the U.S. military and didn't feel he was treated as an American and soldier should be.

As of the end of last week, the national offices of the Council on American Islamic Relations (CAIR) said it had heard of only one threat, which was aimed at a Dallas Muslim.

Some of the thousands of Muslims in the U.S. military worry that this one burst of violence could unravel their efforts to be accepted as loyal, dedicated soldiers, and that their reputation could be another casualty of the attack. But others say the problems for Muslims in the military come only from a small minority of bigots in uniform.

Ashkan Bayatpour, 25, a U.S. Navy veteran and the American-born son of Iranian immigrants, told the Associated Press: "Just as this guy in Fort Hood doesn't represent every single Muslim in the world or in this country, the few ignorant or racist people that remain in the military, they are so few and far between, they do not represent the military at large."

Hasan did not hide faith – or his military profession. He wore his military uniform to Friday prayers, fellow members of his mosque reported.

Leaders of the American Muslim Armed Forces and Veterans Affairs Council predict that any backlash would be limited. Military personnel often have a more sophisticated world view after traveling the globe and working with people from diverse backgrounds, said Abdul-Rashid Abdullah, a U.S. Army veteran who served from 1991 to 1998. Most importantly, he said, they form strong bonds with their fellow soldiers.

In his weekly radio and Internet address, President Barack Obama noted those bonds, too. "They are Americans of every race, faith and station. They are Christians and Muslims, Jews and Hindus and non-believers," Obama said. "They are descendants of immigrants and immigrants themselves. They reflect the diversity that makes this America. But what they share is a patriotism like no other."

There is no exact count of Muslims in the military. The Pentagon lists 3,557 Muslims out of 1.4 million U.S. service members. However, the figure should be viewed as a minimum because the disclosure is voluntary, military officials said.

The Army trains its personnel to be sensitive to Muslim culture because it is anxious to avoid frictions with local populations in Iraq and Afghanistan. But there can be a difference in how more educated officers reflect on that training and how less educated enlisted men, some with a tendency to think in simple black and white terms, react to it.

Bob Jenkins, a spokesman at Fort Campbell in Kentucky, said that the notion of fighting an enemy with commonalities to U.S. service members is not new and that other soldiers have had to come to terms with that in past conflicts.

"There is really no difference if you get someone who is of Italian heritage in World War II and send them into Italy to fight the people who backed Mussolini," he said. "There are some things you have to come to grips with."

The armed services have a clear, well-known policy against discrimination, said Imam Yahya Hendi, a Georgetown University chaplain who has worked for more than a decade with U.S. military personnel. The military requires service members to respect others' beliefs, and he has found officers take complaints of prejudice very seriously.

He noted that the U.S. military is desperate to recruit American Muslims and make them feel welcome because, like many government agencies, the Armed Services need people with knowledge of Islam, Muslim culture and the Arabic language. Hendi has traveled to military bases nationwide, including several visits to Fort Hood, holding classes for soldiers deploying to Afghanistan and Iraq.

Still, Hendi said policies and sensitivity training can't stop every snide comment. He said rank-and-file Muslim service members have complained to him of being asked whether "you guys always pray to destroy us," or, "are you going to do what your people do?'"

Hendi said he has encountered a few people during his training sessions who consider the Muslim religion – not extremist individuals – the real threat to national security. "There are always individuals who don't want to believe what you're saying about Muslims or Islam," he said. "They think you're evil."

Bayatpour, an Iranian American who grew up in Mobile, Alabama, and served in Iraq, said it was rare to hear offensive comments about his religion from fellow service members. He said he found his presence in the Navy encouraged questions about what Islam teaches, and would often spark conversation about commonalities between Islam and Christianity.

Lt. Col. Abdul-Rasheed Muhammad, 57, the U.S. military's first Muslim chaplain, told the Associated Press he's experienced little prejudice in the Army because of his religion and has heard of few complaints from other Muslims on base. Off base is different, he said. He has been delayed at airports and had his luggage searched.

Retired Marine Col. Doug Burpee, 52, who converted to Islam three decades ago to marry a Muslim woman, said fellow Marines were more curious about his religion than upset by it.

He does remember Marines of similar rank chiding him, saying things such as, "Burpee's a traitor. He was a Christian and [now] he's a Muslim." But he dismissed those comments as "guy stuff" – the tendency of American males to be verbally rough, thinking it's amusing, and also seeing it as a test of whether the targeted person can take it and fit in.