What was originally envisioned as a training cadre of about 350 American law enforcement officers was quickly scaled back to 190 and then to 100. The latest restructuring calls for 50 advisers, but most experts and even some State Department officials say even they may be withdrawn by the end of this year.

The training effort, which began in October and has already cost $500 million, was conceived of as the largest component of a mission billed as the most ambitious American aid effort since the Marshall Plan. Instead, it has emerged as the latest high-profile example of the waning American influence here following the military withdrawal, and it reflects a costly miscalculation on the part of American officials, who did not count on the Iraqi government to assert its sovereignty so aggressively…

Last month many of the Iraqi police officials who had been participating in the training suddenly refused to attend the seminars and PowerPoint presentations given by the Americans, saying they saw little benefit from the sessions.

The Iraqis have also insisted that the training sessions be held at their own facilities, rather than American ones. But reflecting the mistrust that remains between Iraqi and American officials, the State Department’s security guards will not allow the trainers to establish set meeting times at Iraqi facilities, so as not to set a pattern for insurgents, who still sometimes infiltrate Iraq’s military and police.