JALALABAD, Afghanistan: Afghan forces, backed by US airstrikes on Tuesday, ramped up an offensive against the Islamic State group in their eastern stronghold following the militants claiming the Kabul attack. Afghani troops seized large parts of the mountainous district of Kot in Nangarhar province, a key IS stronghold where the militants had built sharia courts and training camps, displaying their trademark black flag. Some 120 militants were killed in the operation including an IS commander named Saad Emarati, Provincial Spokesman Attaullah Khogyani said. “They have been taught a lesson for their crimes. We will wipe out IS from Nangarhar,” Defence Ministry Spokesman Mohammad Radmanish said. The offensive follows the twin bombings on Saturday that tore through crowds, as they protested over a major power line in Kabul, killing 80 people and leaving hundreds of others maimed. IS, which controls territories across Syria and Iraq, claimed the bombings in a statement carried by its affiliated Amaq news agency.