Omar was radicalised at an early age and joined Harkat ul-Ansar, one of the militant groups fighting Indian rule in Kashmir. When the U.S invaded Afghanistan in 2001, Khorasani set up an office of Harkat in Mohmand Agency, where he recruited fighters for ‘jihad’ against the American forces. Omar gained prominence, after vowing to avenge the Lal Masjid operation, and seized the shrine of a famous anti-colonialist fighter in the village of Ghazi Abad during the summer of 2007, renaming it Lal Masjid (Red Mosque).