In the days since the shootings, the question of Muslims serving in the U.S. military has been unavoidable. In one sense, the question is hardly new. It arose in the first Gulf War when Muslims asked if it could be allowable to serve in the U.S. military when action was taken in or against a Muslim majority nation. Clearly, the question now arises in the case of Major Nidal Malik Hasan. Evidence that Hasan cried out a Muslim expression during the attack, that he had visited a mosque linked to Muslim extremism, and that he had been in contact with suspected Islamic terrorist groups like Al Qaeda only served to add urgency to the questions.

The United States military is made up of citizen soldiers, and is an all-voluntary force. These citizen-soldiers defend our freedoms and constitutional rights, and they do not surrender their constitutional rights when they put on the uniform. Our cherished rights of religious belief and expression are not canceled when individuals enter the Armed Forces.

At the same time, the military is a unique institution -- a fact recognized by law. Voluntary enlistment in the Armed Forces entails the assumption of certain limitations and responsibilities that are necessary for the maintenance of military order and effectiveness.

Given our commitment to religious liberty, we must make every reasonable accommodation to the religious beliefs of military personnel. These accommodations range from the provision of military chaplains and chapels to the category of conscientious objector, based in religious conviction. Complex questions do arise, and in the context of deployment to battle the questions of accommodating religious belief can erupt in excruciatingly difficult forms.

Service in the military is open to all, regardless of religious faith. In our constitutional republic, that is as it should be. Those who wear the uniform of the U.S. Armed Services take an oath to "support and defend the Constitution of the United States." To take that oath and put on that uniform is to accept a solemn and sacred responsibility to defend the United States. If religious beliefs conflict with this oath, the individual should never enter the Armed Forces.

We know enough by now to know that Major Hasan was a deeply troubled man. There is now no way to isolate his deeds from his Muslim identity. We cannot read his heart, but we can read of his contacts, statements, and actions. There is already a reactivated debate among Muslims about the ethics of Muslims serving in the Armed Forces in Muslim lands.

It is not fair to generalize Major Hasan's actions to the entire Muslim community, but there is also no way to ignore the fact that Major Hasan's Muslim beliefs were involved in his motive for the killings. This will take time to sort out.

In the meantime, the U.S. Armed Forces should make every effort to accommodate the religious beliefs and convictions of its personnel. That is what we owe to those who put their lives on the line to defend our freedoms. But they owe the entire nation -- and first of all their fellow soldiers --  the commitments of loyalty, obedience, respect, and protection.

The military cannot accommodate any belief system that undermines those commitments. No nation can accommodate those who would turn themselves into terrorists against their own neighbors, citizens, and fellow soldiers.