Over at Intel News, Ian Allen makes a good argument for not assassinating terrorists. The argument fails to convince though because it is based on the premise that that terrorists are mere criminals. While that is the traditional view, US policy after 9/11 is to treat terrorists as enemy combatants.
As Scott Reid pointed out in 2004
The recent activities of transnational1 terrorist organizations have transcended the realm of mere criminality. For more than a decade, the Al Qaeda terror network has repeatedly attacked U.S. citizens, property, and military interests, to wit: the World Trade Center in 1993, the U.S. Embassies in Kenya and Tanzania in 1998, the U.S.S. Cole in a Yemeni port in 2000, and the World Trade Center and Pentagon on September 11, 2001. Al Qaeda has been characterized by one observer as a “modern army” with combat power, considerable financial resources, decentralized command and control, and operational reach into all the nations of the world. The President has responded to Al Qaeda’s asymmetric attacks with military force, which perversely elevates the status of these terrorists from criminals to enemies. When the Taliban government of Afghanistan persisted in providing Al Qaeda with a safe haven, it became our enemy as well.
Enemy combatants (whether lawful or unlawful) are subject to the international law of armed conflict, not criminal rules. That means they are fair game, anytime, anywhere, subject to the rules of war. Convince me that they are mere criminals, then I'll support an assassination ban and we can send in the FBI. Until then, they are targets.