The military's effort to build a seasoned corps of expert officers for the Afghan war, one of the highest priorities of top commanders, is off to a slow start, with too few volunteers and a high-level warning to the armed services to steer better candidates into the program, according to some senior officers and participants. The groundbreaking program is meant to address concerns that the fight in Afghanistan has been hampered by a lack of continuity and expertise in the region among military personnel. But some officers have been reluctant to sign up for an unconventional career path because they fear it will hurt their advancement -- a perception that top military leaders are trying to dispel as they tailor new policies for the complex task of taking on resilient insurgencies in Afghanistan and Pakistan. Each military branch has established career paths, and this type of focus would take people off those routes. The difficulties with the program came to light when the chairman of the Joint Chiefs of Staff, Adm. Mike Mullen, in an unusual rebuke within the Pentagon's uppermost circle, admonished the chiefs of the four armed services three weeks ago for not always providing the best people. The program -- which is expected to create a corps of more than 900 officers and soldiers who will work on Afghanistan and Pakistan issues for up to five years -- was announced with much fanfare last fall. So far, 172 have signed up, and Mullen has questioned whether all of them are right for such a critical job. In a memo sent last month to the chiefs of the Army, Navy, Air Force and Marine Corps, Mullen expressed concern that the services were not consistently providing the 'best and the brightest leaders' for the program's corps of officers and soldiers, who will work in the field and at headquarters. The program was conceived as a way to develop a pool of uniformed experts who would spend several years rotating between assignments in Afghanistan or Pakistan, and desk jobs in Washington or other headquarters working on the same regional issues. At the outset, volunteers receive cultural training and 16 weeks of language instruction in Dari, Pashto or Urdu. In time, they are expected to provide a deep bench for assignments that could significantly alter the course of the war. The military expects to fill all 912 positions by the summer of 2011. The first class of volunteers that started instruction in November included 102 people, but a second class that started Monday had only 60 people. 