KABUL: The Taliban captured the northern Afghan city of Kunduz in a massive assault Monday involving hundreds of fighters, and now control a major urban area for the first time since the 2001 United States (US)-led invasion.

The fall of Kunduz marks a major setback for government forces, who have struggled to combat the Taliban since the US and North-Atlantic Treaty Organization (Nato) shifted to a supporting role at the end of last year.

Read: 'Northern Afghan city of Kunduz collapses into hands of Taliban'

Afghan military reinforcements have been sent to recapture Kunduz.

The US also launched airstrikes against the Taliban insurgents on Tuesday to show support for the Afghan troops.

The Kunduz assault highlighted the resiliency of the Taliban following the revelation earlier this year that their reclusive longtime leader Mullah Mohammad Omar died two years ago.

A bitter internal dispute over the appointment of his successor, Mullah Akhtar Mansoor, has yet to be fully resolved, but seems to have had little impact on the battlefield.

Read: US air strike hits Taliban in captured Afghan city: Nato