Most importantly for the U.S. military, on November 28, 2005, the Department of Defense (DOD) issued a directive setting forth a new DOD policy regarding stability operations, particularly peacekeeping and related post-conflict operations. These requirements have been problematic for many policymakers and for the U.S. armed forces, which have preferred to confront an enemy with the degree of force necessary to quickly defeat armed opponents (often referred to as "decisive" or "overwhelming" force) and to reserve its highly-skilled troops for combat missions. U.S. military experiences in Somalia and Haiti stigmatized peacekeeping and nation-building for many Members as an inefficient and inappropriate use of military resources, leading to restrictions on U.S. involvement in dealing with deteriorating conditions in the Balkans in the mid-1990s. The terrorist acts against the United States of September 11, 2001, changed the debate. In the wake of U.S. military action in Iraq, the question of continued U.S. military involvement has been framed in terms of whether the U.S. military should do "nation-building," and if it does, how it should prepare for it. Very few U.S. military personnel currently serve under U.N. command. Roughly 700 U.S. troops serve in the Sinai-based Multilateral Force and Observers (MFO) ad hoc coalition operation, which has no U.N. affiliation. An ongoing drawdown is scheduled to reduce the number still further. A small number of U.S. troops, some 100 as of the end of 2006, work with the NATO Headquarters unit providing support to the EU in Bosnia. As a result, a large number of U.S. troops in Afghanistan which previously had been attached to the U.S.-led Operation Enduring Freedom (OEF) were assigned to ISAF as of early October 2006. The Extended U.S. Military "Stabilization" Presence in Iraq19

U.S. troops in Iraq are engaged in a wide variety of activities, the most visible of which are counterinsurgency operations, but some of which are generally classified as peacekeeping duties. Although the current military occupation of Iraq falls in a gray area that defies easy definition, with a level of instability that many define as low-intensity conflict rather than peace enforcement, many of the activities that the U.S. military has undertaken there also have been undertaken in past peacekeeping operations. DOD Directive 3000.05 sets forth a radically new policy regarding missions known as "stability" operations, a major subset of which are peacekeeping and other peace operations. The Directive on Military Support for Stability, Security, Transition, and Reconstruction (SSTR) Operations designates stability operations as "a core U.S. military mission." Nevertheless, events in Iraq since the United States invaded in 2003 have reinforced arguments that still greater efforts must be made to raise the possibilities for successful transitions. Force Size and Structure

Whether U.S. military forces should be sized and organized specifically to facilitate peacekeeping and related stability operations has been a longstanding issue. Others have urged more extensive changes in the force to better accommodate such missions. Some analysts view U.S. military nation-building as an essential element in the U.S. toolkit to respond to the Congressionally-mandated 9/11 Commission's recommendation to use all elements of national power "to keep possible terrorists insecure and on the run...." 
In immediate post-conflict situations, or extremely dangerous environments, military forces may be the only personnel available to perform such tasks. The Global Peace Operations Initiative29

The Bush Administration proposed a five-year, multilateral Global Peace Operations Initiative (GPOI), to prepare other, largely African, nations to participate in peacekeeping operations.
The 110th Congress may well face several decisions regarding the preparation of U.S. military forces for stability missions, a major subset of which is peace operations. A November 28, 2005, Department of Defense (DOD) directive that designates stability operations as "core missions" of the U.S. military marks a major shift in attitudes regarding peacekeeping and related stability operations (also known as stabilization and reconstruction operations). Since then, DOD has worked to define specific changes that must be made to better accomplish such missions, some of which the U.S. military could implement on its own, while others would require Congressional approval.
For well over a decade, some Members of Congress expressed reservations about U.S. military involvement in peacekeeping operations. The Bush Administration initially opposed such missions and took steps to reduce the commitment of U.S. troops to international peacekeeping. This action reflected a major concern of the 1990s: that peacekeeping duties had overtaxed the shrinking U.S. military force and were detrimental to military "readiness" (i.e., the ability of U.S. troops to defend the nation). Many perceived these tasks as an inefficient use of U.S. forces, better left to other nations while the U.S. military concentrated on operations requiring high-intensity combat skills. Others thought that the United States should adjust force size and structure to accommodate the missions.
The events of September 11, 2001, brought new concerns to the fore and highlighted the value to U.S. national security of ensuring stability around the world. The 9/11 Commission report, which cited Afghanistan as a sanctuary for terrorists, pointed to the dangers of allowing actual and potential terrorist sanctuaries to exist. In 2003, the U.S.-led occupation of Iraq, often referred to as a "stabilization and reconstruction" operation (which manifests some characteristics of a peace operation), reinforced the argument.
Thousands of U.S. military personnel currently serve in or support peacekeeping operations, although the number of troops serving in U.N. operations has decreased dramatically since the mid-1990s to some 26 in five operations under U.N. control. In the Balkans, some 1,700 U.S. troops serve with the NATO Kosova Force (KFOR). About 35,000 more serve in or support peacekeeping operations in South Korea, and roughly 700 serve in the Sinai. In Iraq and Afghanistan, U.S. troops are involved in a variety of stability tasks, including "nation-building" activities that have been undertaken in some peacekeeping operations as well as combat operations.
A major issue Congress continues to face is what, if any, adjustments should be made in order for the U.S. military to perform peacekeeping and stability missions—in Afghanistan, Iraq, or elsewhere—with less strain on the force, particularly the reserves. Of particular interest is whether the size and configuration of U.S. forces, especially the Army, should be further modified. Additional issues are whether to augment civilian and international capabilities in order to take on more of the burden.