Heres the trickiest counterterrorism puzzle for US policymakers: How do you stop al-Qaeda from attacking the American homeland without getting bogged down in protracted wars against insurgents? One answer would be to establish deterrence in the long war against Islamic extremism, like the standoff that developed between the United States and the Soviet Union during the Cold War. The Soviets were obviously a far bigger adversary, but the basic logic is the same: Both sides have deadly weapons, but if you dont shoot at us, we wont shoot at you. The Obama administration hasnt declared any such neo-deterrence strategy, but you can see the outlines of one emerging in the administrations unannounced targeting policy for armed Predator drones, which have been Americas deadliest weapon against al-Qaeda. The latest illustration of the drones precision power came in Fridays attack on Anwar al-Awlaki, a leader of al-Qaeda in the Arabian Peninsula. The strike over northern Yemen, which followed days of silent surveillance, killed Awlaki and Samir Khan, the editor of an al-Qaeda online magazine called Inspire. Both were US citizens. But in recent weeks a subtle limit has emerged in drone policy: Despite calls by some US officials for drone attacks against the training camps of AQAP and al-Shabab, the al-Qaeda affiliate in Somalia, neither has been targeted. Thats a deliberate policy decision aimed partly at preventing the spread of a Taliban-style insurgency to new theatres, such as Yemen and Somalia. The United States claims it has legal authority for such so-called signature strikes on training camps of al-Qaeda affiliates, under both the congressional Authorisation for Use of Military Force passed in September 2001 and the international law of self-defence. This broad legal authority for targeting was outlined by John Brennan, the White House counterterrorism chief, in a Sept. 16 speech at Harvard. But as a matter of policy, Brennan and other top officials have decided (for now) against such strikes in the new battlegrounds, in part to prevent an ever-widening war that fosters the very Islamic insurgency we want to contain. Indeed, officials say there havent been any signature strikes against camps (as opposed to individuals) outside Pakistans tribal areas, where al-Qaedas core leadership is based. A senior administration official explains the policy this way: If individuals target us, if they are in the chain of command for attacks against Americans, then the United States will authorise direct action putting such individuals on the capture or kill list that triggers a drone attack. But, the official cautions, We dont want to get involved in a domestic confrontation inside Yemen or Somalia, or increase anti-U.S. sentiment in those places. There is a deterrence formula implicit in this policy: So long as Somalias al-Shabab remains an insurgent movement fighting the Transitional Federal Govt, the US while supporting the Somali authorities wont use drones. That weapon is reserved for those who directly threaten the United States. Al-Shabab can increase the danger to themselves if they attack us, or engage in actions designed to hurt our people, says the official. We can act in self-defence, but also to send the message that if you threaten us, you do so at your own peril. This calibrated approach has reassured key US allies, such as Britain, that have large Muslim immigrant populations and were worried about the blow-back from US campaigns against al-Qaeda affiliates. There was concern that it was a blanket approach, concedes the US official. I asked the Obama administration official about the due process problem. On what basis does the United States issue what amounts to a death warrant against an American citizen, such as Awlaki? The official answered that reviews are conducted by an inter-agency committee of lawyers, and also by a committee of deputies of all key departments and that strike orders require unanimous agreement. Thats only partly reassuring; a more rigorous legal process would be better, such as the secret court that rules on foreign-intelligence requests for search warrants. Whats good about the evolving drone policy is that it recognises the need for limits. We dont have enough drones to kill all the enemies we will make if we turn the world into a free-fire zone. And theres something important in the hint of a deterrence strategy: This is how wars end in the part of the world where al-Qaeda arose through a balance of mutual restraint that makes a de facto truce possible, even between the most bitter enemies. Washington Post