American jets launched airstrikes in northern Afghanistan on Tuesday in support of an army effort to retake the city of Kunduz from Taliban militants.

Afghan forces engaged the insurgents the same day. They had been driven to the outskirts of the city following a summer Taliban offensive that culminated in them occupying its center.

Kunduz is Afghanistan’s sixth largest city and the first provincial capital to fall to the Taliban since the Islamist movement was toppled in an American-led invasion in 2001.

The multiethnic Kunduz Province, bordering Tajikistan, was one of the areas where the Northern Alliance resisted Taliban rule in the late 1990s. A contingent of NATO troops, led by Germany, was stationed there from 2003 to 2013.

The province was largely peaceful until 2009 when successful counterinsurgency operations in the Taliban’s southern heartland compelled the group to shifts its focus to the more lightly-guarded north.

Most German and other European forces have withdrawn from Afghanistan.

At its peak, the Western alliance had some 130,000 troops in the country. Less than 10,000 American soldiers remain, serving in support and advisory positions under the banner of Operation Resolute Support.