Al Qaeda is not a nation-state and it has not signed the Geneva Conventions. It shows no desire to obey the laws of war; if anything it directly violates them by disguising themselves as civilians and attacking purely civilian targets to cause massive casualties.

The United States has used force abroad more than 130 times, but has only declared war five times - the War of 1812, the Mexican-American War, the Spanish-American War, and World Wars I and II.

Our enemy now is a stateless network of religious extremists. They do not obey the laws of war, they hide among peaceful populations and launch surprise attacks on civilians. They have no armed forces per se, no territory or citizens to defend and no fear of dying during their attacks.

I think it can be very important for the president to seek congressional approval for war , even though not constitutionally required to do so, in certain situations. It makes sense to go to Congress to signal our national resolve and our willingness to fight to defend other nations or the freedom of their peoples.

I believe that the power to declare war is most important in limiting the powers of the national government in regard to the rights of its citizens, but that it does not require Congress to give its approval before the president uses force abroad.

An American leader would be derelict of duty if he did not seek to understand all his options in such unprecedented circumstances. Presidents Lincoln during the Civil War and Roosevelt in the lead-up to World War II sought legal advice about the outer bounds of their power - even if they did not always use it. Our leaders should ask legal questions first, before setting policy or making decisions in a fog of uncertainty.

Without territory, it does not even have the resources to provide detention facilities for prisoners, even if it were interested in holding captured POWs.