ISLAMABAD (AP) — Pakistan launched a ground offensive against militant strongholds near the Afghan border on Monday after evacuating nearly half a million people from the region, the army said, in the most significant escalation of a two-week long operation to root out insurgents trying to overthrow the government.

The ground offensive is the second phase of a long-awaited operation against militants in the North Waziristan tribal area, a lawless, mountainous stretch of land in northwest Pakistan. The military announced the operation on June 15 but has mostly limited its tactics to airstrikes while giving time to hundreds of thousands of people to pack up their belongings and leave to safer areas.