Afghanistan

United States
In mid-October 2015, President Obama reversed plans to reduce the U.S. military presence to a small protection force in Kabul, saying he would prolong the engagement by maintaining a force of 9,800 through most of 2016. The U.S. troops used the mission to train and advise Afghan security forces, as well as conduct counter-terrorism operations; however, the U.S. reputation in the region was damaged on October 3 when an airstrike killed 22 patients and staff in a Doctors Without Borders hospital in Kunduz.

Islamic State of Iraq and Syria
Islamic State seized swathes of territory in Iraq and Syria throughout 2014 and 2015, which allowed the group to mount attacks on Afghan security forces in the eastern province of Nangarhar by the end of the year. Islamic State had coalesced since the middle of 2015 in Nangarhar and Kunar provinces and was fighting the Taliban for several months. Indeed, the estimate of between 1,000 and 3,000 members of Islamic State forced the Taliban to re-direct some resources away from fighting Afghan security forces.

Militants also took to the airwaves in eastern Afghanistan to win recruits as they tried to build strength and replace the Taliban as the leading force in the insurgency. The broadcasts encouraged young people to find a sense of direction in the radical movement.

Taliban
The Taliban captured the northern strategic city of Kunduz on September 28, 2015, in an offensive that took the Afghan forces by surprise. Fighting was confined mostly to the outskirts of the city until the Taliban withdrew on October 13, ten days after a U.S. airstrike on a Doctors Without Borders hospital killed at least 2 staff and patients, not without freeing hundreds of fighters from Kunduz prison. Another high-profile attack occurred at Kandahar Airport on December 8, 2015, killing 50 people.

In mid-December 2015, Helmand Province, a center of opium production and a Taliban heartland that British and American troops struggled to control for years, was threatened by the Taliban after 90 members of the security forces were killed between December 19-20. Despite President Ashraf Ghani's international aid and training assistance from thousands of NATO troops still stationed in Afghanistan, his government pushed to reopen talks with the Taliban, a sign that Afghan security forces could not control the insurgency. Indeed, on December 21, six American troops were killed when a suicide bomber on a motorbike struck their patrol near Bagram air base, the deadliest attack on U.S. forces in 2015, as the Taliban tightened their grip in Helmand.