"Everything in war is very simple," wrote Prussian military thinker Carl von Clausewitz. "But the simplest thing is difficult." Put another way, a soldier's job in combat is to kill or capture the enemy, but how a soldier goes about this is rarely simple, and with new battlefield technologies, the ways in which this goal can be accomplished have expanded--and been complicated­--tremendously.

Take the case of Al Qaeda in Iraq leader Abu Musab al-Zarqawi. He was killed in 2006 when U.S. Air Force pilots in F-16Cs dropped guided munitions on a house in which he was hiding. Zarqawi was tracked, located and killed. Simple enough. But consider the events behind the attack. They began when Jordanian intelligence agents received a tip that Zarqawi was seeking the advice of a religious leader, information they passed on to the Americans, who tasked unmanned aerial vehicles (UAVs) to monitor the cleric. Eventually the UAVs followed Zarqawi to a farmhouse. Once confirmation of his presence was made, the F-16Cs attacked.

Numerous factors made the strike successful--human intelligence, data analysis, deployment of conventional air and ground assets, use of advanced technology--and some might say the events leading up to the strike are less important than the result. But to the services that are fighting for what is sure to be a smaller slice of the Pentagon's budgetary pie in coming years, it's critical to know which tactics are most effective in winning the irregular wars that dominate regional and local conflicts.

For the U.S. Army, which has embraced the realities of irregular warfare and rapidly exploited emerging technologies, the transformation has been painful at times, creating deep fissures between those who want to use the lessons of Iraq and Afghanistan to radically remake the force, and those who worry that traditional combined arms skills will fall by the wayside in the rush to embrace stability and counterinsurgency (COIN) operations.

At the heart of this is doctrine, and the Army has been in front on this, too, releasing new doctrine papers on COIN and stability operations in recent years. The next step in this, which will look beyond COIN, is being undertaken by Training and Doctrine Command, which has assigned Brig. Gen. H.R. McMaster to retool the service's Capstone Concept, a document that fleshes out how it will fight future wars.

Heading up a 20-person team, McMaster hints at what the concept might look like in a statement that his team is "recognizing some of the limitations in technologies that were designed to improve situational understanding and situational awareness." He added that "we understand now how enemy countermeasures can place what we need to know about the enemy and what we need to know about the situation outside the reach of technology."

"The issue of doctrine is huge," says P.W. Singer of the Brookings Institution. "Choose the right doctrine and you've found the blitzkrieg of the 21st century; choose the wrong doctrine and you've come up with the Maginot Line." One of the major tasks for the Army is to try to articulate, to itself as well as to members of Congress who fund procurement, how it plans to exploit their greatest advantage emerging manned and unmanned systems and new communication and intelligence technologies. As Singer says, "the Army is trying to figure out how to use technology as an enabler" and create the conditions under which it retains tactical battlefield dominance.

Although the use of technology in Iraq and Afghanistan has produced undeniable tactical successes, it has yet to be tied to an overall strategy or doctrine. But that's coming. Examples of how the Army will transform itself in the future include the increasing use of lethal UAVs--the Army recently launched its first missile from a UAV in Afghanistan--as well as employment of the Land Warrior communications suite that platoon leaders in Stryker units in Iraq and Afghanistan have worn, better video feeds that can be passed quickly around the battlefield and non-lethal technologies. And all of those will have to start to shape organizational behavior, Singer says, from "tactics to doctrine to laws, ethics, questions about accountability, leadership within the force, personnel systems, you name it. And that is a ripple effect."

While this ripple has been working its way though the service, the debate over it is nothing compared to the emotional battle being waged over how much emphasis the Army should place on COIN and stability operations, versus keeping its edge sharpened in combined arms warfare.

One outspoken participant in the debate is Col. Gian Gentile, who commanded the 8/10 Cavalry armored reconnaissance squadron in Iraq and is now a history professor at West Point. Gentile has written widely over the last several years about how he believes the Army's ability to practice combined arms warfare "has atrophied" due to the focus on COIN. He fears that some in the Army, as well as influential voices outside it, are pushing too hard to remake the service into a counterinsurgency force.