A convoy of army forces has been ambushed by the Taliban in western Afghanistan, killing 11 Afghan soldiers in a grueling five-hour-long firefight. The attack came as Afghan forces prepare to face the first fighting season without NATO combat support.

The attack happened in the Karokh district of Herat, where an army logistics supply unit fell victim to an ambush by the Taliban. Najibullah Najibi, spokesman for the 207 Zafar military corps, stated that the fighting lasted five hours, with 11 Afghan soldiers and six Taliban killed in the battle, according to Reuters.

He further stated that at least six other Afghan soldiers were also injured.

Weapons were also acquired by the Taliban after the ambush, in what seems to be an increased offensive against Afghan security forces since launching their annual spring offensive last April, reports BBC news.

This year's offensive, dubbed "Azm" (determination), vows nationwide attacks in what is expected to be one of the bloodiest summers of the decade. This is especially due to the fact that Afghan forces are currently stretched out on numerous fronts. The forces are also facing record high-casualties, according to Al Jazeera.

Afghan forces have been facing a difficult challenge since the withdrawal of most foreign troops last year, when NATO's combat mission in Afghanistan formally ended after 13 years. Despite the departure of the main forces however, a small number of NATO officers have remained behind to provide training and support to local security forces.