US General John Campbell speaks during a ceremony marking the end of ISAF's combat mission in Afghanistan at ISAF headquarters in Kabul on December 28, 2014. NATO formally ended its war in Afghanistan on December 28, holding a low-key ceremony in Kabul after 13 years of conflict that have left the country in the grip of worsening insurgent violence.Getty Images

US and NATO forces formally ended the war in Afghanistan on Sunday (28 December), in a combat mission that has so far claimed the lives of 3,485 foreign troops.

In a joint ceremony held at their Kabul military headquarters, US and NATO forces officially ended their 13-year participation in the Afghan war that began in 2001.

"Together... we have lifted the Afghan people out of the darkness of despair and given them hope for the future. You've made Afghanistan stronger and our countries safer. The road before us remains challenging but we will triumph," said Gen. John Campbell, commander of the US-led International Security Assistance Force (ISAF), while rolling up the ISAF flag and replacing it with the flag of the new international mission, Resolute Support.

ISAF was formed following the September 11 attacks as US-led forces set to defeat the Taliban regime with 50 nations under the US-led coalition supporting the fight.

As part of a transition that is set to begin on 1 January 2015, an estimated 13,500 troops, mostly American, will remain in Afghanistan, reported NBC News.

The troops will train and support the Afghan military forces, as was signed off by Afghanistan President Ashraf Ghani in bilateral security agreements with NATO and Washington when he joined office in September.

Many argue that the timing is wrong as Afghan forces are incapable of fighting the Taliban and other insurgents who have already stepped up violence to destabilize the government.

Meanwhile, Taliban spokesman Zabihullah Mujahid told AFP News, as reported by Sky News: "The US and NATO mission was an absolute failure as today's ceremony shows. They are fleeing from Afghanistan. They have not reached their goals in defeating the Afghan mujahideen."

The US-led war in Afghanistan has so far claimed the lives of an estimated 3,188 civilians and 3,485 foreign troops.

US General John Campbell (L) rolls the flag of the NATO-led International Security Assistance Force (ISAF) during a ceremony marking the end of ISAF's combat mission in Afghanistan at ISAF headquarters in Kabul on December 28, 2014.Getty Images