BASMAYA, Iraq — The U.S.-led coalition is planning for the day when Iraq will be free of the Islamic State group, ramping up training of a future Mosul police force — even as the battle for the rest of the city is briefly on hold.

Sometime during the lull, significant numbers of the security forces are expected to move into villages scattered across the plains of Ninevah province around Mosul and also into parts of the city retaken from IS over the past three months.

The Iraqi military declared Mosul’s eastern half “fully liberated” in January and is now preparing to battle for the city’s western sector — likely to be a much tougher fight in a dense and overcrowded urban environment. The operation to free Iraq’s second-largest city has been the most complex challenge for Iraqi forces to date.

With more than 100,000 soldiers, police, tribal and militia fighters deployed for the offensive, Iraqi leaders are aware that after IS militants are routed from Mosul, a well-trained police force will be needed on the ground — to keep the hard-won victory.