Iraqi aircraft dropped "tens of thousands" of leaflets, some bearing safety instructions for Mosul residents, ahead of an operation to retake the city from militants, the military said.
Iraq has dropped leaflets over Mosul before, and has also done so as part of operations to retake other cities seized by the Islamic State group in 2014 and 2015.
Aircraft dropped "tens of thousands of newspapers and magazines on the centre of the city of Mosul carrying important news... to inform them of updates and facts and victories," said Iraq's Joint Operations Command, which distributed images of some of the leaflets.
One image showed a leaflet containing safety instructions for Mosul residents, urging them to tape over windows to prevent the glass from shattering, to avoid the sites of air strikes for at least an hour after a place is bombed, and saying they should not drive if possible.
The launch of the operation is expected to be announced soon, but it will mark only the start of a battle that is likely to be the most difficult and complex yet in the war against IS.
A coalition of heterogenous and sometimes rival Iraqi forces will have to fight their way through IS defences to reach the city, in some cases over distances of dozens of kilometres (miles).
Then they will likely seek to surround the city before launching an assault, marking the start of deadly street fighting with die-hard Islamist militants in a city with a large civilian population.
The battle may spark a humanitarian crisis, with the United Nations warning that up to one million people may be displaced by the fighting as winter sets in.
Even the recapture of Mosul will not mark the end of the war against IS, which still holds other territory in Iraq and is likely to turn increasingly to insurgent tactics such as bombings and hit-and-run attacks as it loses more ground.