In pictures: Mosul mission

1 of 6 The US military has begun a major operation to control Iraqi insurgents in the northern city of Mosul.

2 of 6 Some 3,000 US and Iraqi soldiers are now working in Iraq's third-largest and strategically important city.

3 of 6 They are searching through buildings seeking insurgent hideouts and weapons caches.

4 of 6 The people of Mosul, an ethnically mixed group, have simply had to stand by and watch.

5 of 6 The soldiers are from the 3rd Battalion's 21st regiment, known as the Stryker Brigade.

6 of 6 Residents have heard US warplanes and helicopters hovering over the city and the sound of gunfire near the US base.