Last week’s Islamic State bombing of a protest rally in Kabul that killed 80 people and injured over 200 more came amid a major assault by the Afghan army — and U.S. special operations forces — on the group’s stronghold in eastern Afghanistan.

The bombing was by far the Islamic State’s deadliest attack in the country to date, and the worst in the capital since the Taliban was ousted in 2002. The scale of the assault also calls into question comments by Afghan and American officials that the Islamic State had been largely contained to just a handful of districts in the mountainous border region with Pakistan.

The new fighting in the east comes as Afghan security forces struggle to reverse Taliban gains across the country, where the militants now control more territory than at any point since 2001, and have inflicted record casualties on government forces. In 2015, about 16,000 Afghan soldiers and police were killed or wounded, a number which was already a significant increase from 2014’s record of 12,500 casualties.

And 2016 promises to be even bloodier. Commander of U.S. and NATO forces in Afghanistan, Gen. John Nicholson, told reporters Thursday that casualties this year are 20 percent higher than last year, as the Afghan army and police continue to grapple with poor leadership, high turnover, and near-constant combat. Washington has spent almost $70 billion since 2002 to build and train the country’s security forces.

Nicholson revealed that American special operations forces have been heavily involved in ground fighting in Nangarhar in recent days, and five commandos have been wounded — three of whom had to be evacuated out of the country for treatment. All are expected to recover.

The revelation that American forces are again engaged in close-quarters combat in America’s longest war comes at a time when President Barack Obama has been slowly walking back his earlier efforts to pull out all American troops by the end of his term in January.

Despite the much-publicized end of the U.S. and NATO’s combat role in Afghanistan in January 2015, American aircraft have continued to target both the Islamic State and the Taliban, and U.S. special operations forces have occasionally engaged in combat while accompanying the Afghan forces they’re mentoring. The most infamous American combat incident came in October, when in the midst of a days-long battle in the streets of Kunduz, U.S. Army Green Berets called in an airstrike that inadvertently struck a Doctors Without Borders hospital, killing 42 civilians.

In January, President Obama signed an order allowing increased U.S. airstrikes on the Islamic State, and in June, did the same for Taliban targets, which U.S. pilots had previously been banned from targeting unless American lives were in danger.

In a nod to the White House’s sensitivities over troop levels in Iraq and Afghanistan, the U.S. forces who have just been rushed to the fight in Nangarhar are not included in the count of the 9,800 U.S. troops currently in the country, as they’re members of the military’s global counterterrorism force and will pull out as soon as their mission is completed.

Gen. Nicholson has recently made an effort to tie the Afghan Islamic State affiliate with the group’s de facto capital in Raqqa, Syria, and last week’s attack in Kabul appear to back up those points. The bombing was aimed at a protest by ethnic Hazaras demanding a major regional power line be rerouted through their areas outside of the capital. Islamic State fighters have claimed the strike came in response to a number of Hazaras having traveled to Syria to fight for the Assad regime against the Islamic State.

“Unless they stop going to Syria and stop being slaves of Iran, we will definitely continue such attacks,” militant commander Abu Omar Khorasani told Reuters.

In Nangarhar, however, Nicholson said fighting in recent weeks has reduced the Islamic State’s numbers from about 3,000 to approximately 1,500, and in the wake of aerial assaults and the push on the ground, many of those fighters are streaming south, farther into the mountains.

By Paul McLeary