After two years of heavy casualties, the Afghan military is trying to retake the initiative in the war against militants with a new offensive against Islamic State group loyalists, an assault that will see American troops back on the battlefield working more closely with Afghan soldiers.

Afghan President Ashraf Ghani recently announced a major assault against fighters loyal to the Islamic State group, who over the past year captured positions along Afghanistan’s eastern border with Pakistan, mainly in Nangarhar province. That goal to uproot IS from Afghanistan has taken on new urgency in the wake of a deadly suicide bombing of a protest march Saturday in Kabul that killed at least 80 people.

The Islamic State group’s Aamaq online news agency quickly claimed responsibility for the attack, the first IS attack in the Afghan capital and one of the deadliest ever to hit Kabul. Ghani, in a live televised address after the bombing, told the nation, “I promise you I will take revenge against the culprits.”

The inexperienced Afghan forces have largely stalled in the fight against Islamic militants ever since most international combat troops withdrew in 2014. American forces that remained shifted to a supporting role and U.S. airstrikes diminished, letting the Afghan military take the lead in carrying out the war.