Backed by a US airstrike, Afghan forces have begun a mission to retake the northern city of Kunduz. Government forces regrouped at Kunduz's outlying airport ahead of Tuesday's counteroffensive. The fall of Kunduz, the provincial capital and home to about 300,000 people on the northern border with Tajikistan, sent panicked residents fleeing and dealt a major blow to Afghanistan's NATO-trained security forces.

"Reinforcements have been deployed to the city," regional police spokesman Sayed Sarwar Hussaini said on Tuesday. "We have retaken the provincial police department and provincial prison," he added.

On Monday, Taliban fighters seized the provincial governor's office in one of the group's biggest territorial gains since being ousted by US-led forces 14 years ago. The stunning assault came a day before President Ashraf Ghani's unity government marked its first anniversary, and looks set to further complicate efforts to resume stalled peace negotiations.

Controlled by German troops from 2003 to 2013, Kunduz has become the least secure of Afghanistan's northern provinces. Clashes escalated in intensity and number beginning in 2007. In 2009, the German commander ordered an airstrike on tanker trucks captured by the Taliban.

The attack killed about 100 people, half of them reportedly civilians siphoning fuel from the trucks. In April 2010, three German soldiers died in a Taliban ambush, the worst losses the Bundeswehr had seen since its inception in 1953. Later that month, a roadside bomb killed another four German soldiers.

'Guerrilla-style low-intensity warfare'

At the UN General Assembly on Monday, chief executive Abdullah Abdullah, who rules alongside Ghani in Afghanistan's power-sharing government, called on Pakistan to keep its promise to crack down on groups carrying out cross-border attacks. Abdullah alleged that some fighters in Monday's Taliban attack had come from abroad.

"We call on Pakistan to do what its leadership promised to us a few months ago when they agreed to crack down on known terror outfits," Abdullah told the General Assembly on Monday. He added that without external support "this guerrilla-style low intensity warfare would have been history by now."

Abdullah expressed optimism, however, that the insurgency would lose in the long run. "These attempts will eventually fail to subdue us," he told the General Assembly.

The UN reported that civilian casualties in combat reached a new high in Afghanistan during the first half of 2015.

mkg/msh (Reuters, AFP, dpa, AP)