Advancing Iraqi troops broke through Islamic State defenses in an eastern suburb of Mosul on Monday, taking the battle for the insurgents’ stronghold into the city limits for the first time, a force commander said.

The fighting came after two weeks of advances by U.S.-backed Iraqi forces who cleared surrounding areas of insurgents, in the early stages of the largest military operation in Iraq since the invasion that toppled Saddam Hussein in 2003.

Commanders have said the battle for the city, the hardline militants’ last big bastion in Iraq, could take months. […]