According to this Pentagon concept paper, the point of 21st-century deterrence is to "decisively influence the adversary's decision-making calculus in order to prevent hostile actions against U.S. vital interests."
Terrorists planning an attack inside the United States might not be deterred by the threat of nuclear retaliation - even if the U.S. could find and target them. But they might be persuaded against an attack if they were convinced they would fail, or that an attack would only stiffen American resolve, or that they'd be destroyed in retaliation.
Another approach is suggested by the current debate inside radical Islamic circles about the morality and effectiveness of causing civilian casualties. The United States, Jenkins suggests, ought to be enlisting disillusioned Jihadis to argue against civilian casualties.
The key to this approach is viewing all adversaries, including rogue states such as North Korea, as well as terrorists, as acting in accordance with their own internal "rational calculus," Dunn argued in his paper.
The trick is to discover that calculus and turn it to America's advantage.
That will also require agile, coordinated responses from a wide range of U.S. agencies. Influence decisions by a terrorist organization, for example, might link the eavesdropping capability of the National Security Agency, agents run by the CIA, the Army's psychological operations units and the State Department's public diplomacy specialists.
Another deterrence operation might involve the Treasury and Commerce departments to freeze international funds and impose other financial sanctions to deter bad behavior.
Deterrence might look a lot like Iraq's Anbar Province, where painstaking U.S. military diplomacy helped bring disaffected former insurgents around to oppose al-Qaida extremists.
It might also include influencing decision-making by threatening adversaries with death.
"For hostile dictators, it is a powerful deterrent to know that America is willing and able to target their regimes directly," President Bush said in a May 28 speech at the Air Force Academy in Colorado Springs, Colo.
But even the Defense Department document observes that "the adversary may find the threat of U.S. military action non-credible," as al-Qaida apparently did as it pulled off the 1998 embassy bombings and planned for the Sept. 11 attacks.
Could this complicated approach really work? Almost nobody thinks it would be easy.
The new National Defense Strategy issued by the Defense Department in June concludes that in some cases "deterrence may be impossible." It advocates strengthening defenses and "post-attack recovery."
The White House national security adviser, Stephen Hadley, insisted in a speech last winter that "deterrence can still play a role" against terrorism. But rather than trying to understand and manipulate adversaries' decision-making, he said they could be deterred by the United States acting to build better defenses and threatening those who support or harbor terrorists.
