Following a massive attack in Kabul, the Afghan military has launched a major offensive against the Islamic State group in the country’s far eastern region near the border with Pakistan, Afghan and U.S. officials said on Tuesday.

The offensive began over the weekend in Nangarhar province, where IS has had a presence for the past year, said Dawlat Waziri, spokesman for the Defense Ministry.

The offensive, part of the government’s Operation Shafaq — or Dawn in Pahsto— started hours after an IS suicide bomber killed at least 80 people who were taking part in a peaceful demonstration in Kabul on Saturday.

It was the deadliest attack to hit the Afghan capital since the 2001 U.S.-led invasion.