BAGHDAD — In a move that could portend a strategy change, the commander of American forces in northern Iraq said yesterday that he has proposed reducing his troop levels and shifting next year to missions focused less on direct combat.

Army Major General Benjamin Mixon told the Associated Press that if current trends hold, he would like to begin this troop reduction and change in mission in Ninevah province, where he said Iraqi army forces already are operating nearly independently. He has proposed shifting the province to Iraqi government control as early as August.

Ninevah’s capital is Mosul, the country’s third largest city.

If put in place, General Mixon’s approach would not necessarily mean an overall reduction in American troops early next year. It could mean shifting several thousand troops from General Mixon’s area to other parts of Iraq for some months.

That, however, could mark the beginning of a phased move away from the heavy combat role that American troops have played, at a cost of more than 3,600 American deaths, for more than four years. That, in turn, could lead to the first substantial American troop reductions beginning in the spring or summer — a far slower timetable than many in Congress are demanding.

General Mixon is not the only American commander contemplating a repositioning or reduction of American troops in the months ahead.

Colonel John Charlton, commander of the 1st Brigade, 3rd Infantry Division, who leads a task force of 6,000 American soldiers in a section of Anbar province that includes Ramadi, said in an interview Friday that by January, he might be ready to take a 25% troop cut if the Iraqi police, numbering about 6,000 now, are made stronger by then.

“The police are the keys to maintaining security from Al Qaeda,” Colonel Charlton said.

General Mixon acknowledged that an American shift in northern Iraq meant risking gains made over recent years. But he said it would have important political benefits in Baghdad.

“To be perfectly frank with you, it puts the Iraqi central government in a position of having to assume responsibility for the security situation,” General Mixon said in a telephone interview from his headquarters at Camp Speicher, near the city of Tikrit.