Gen. John Campbell opens the "Resolute Support" flag during a ceremony at the ISAF headquarters in Kabul, Afghanistan, Sunday, Dec. 28, 2014.   (AP Photo/Massoud Hossaini) 

(NEWSER) – The United States and NATO formally ended their war in Afghanistan today with a ceremony at military headquarters in Kabul as the insurgency they fought for 13 years remains as ferocious and deadly as at any time since the 2001 invasion that unseated the Taliban. The symbolic ceremony marked the end of the US-led International Security Assistance Force, which will transition to a supporting role with 13,500 soldiers, most American, starting Thursday. Gen. John Campbell, commander of ISAF, rolled up and sheathed the green and white ISAF flag and unfurled the flag of the new international mission, called Resolute Support. "Resolute Support will serve as the bedrock of an enduring partnership" between NATO and Afghanistan, Campbell said. He paid tribute to the international and Afghan troops who have died fighting the insurgency, saying: "The road before us remains challenging but we will triumph."

As Afghan forces assume sovereignty, the country is without a Cabinet three months after President Ashraf Ghani's inauguration, and economic growth is near zero due to the reduction of the international military and aid juggernauts. The United States spent more than $100 million on reconstruction in Afghanistan, on top of the $1 trillion war. This year is set to be the deadliest of the war, according to the UN, which expects civilian casualties to hit 10,000 for the first time since 2008. This has also been a deadly year for Afghanistan's security forces—army, paramilitary, and police—with around 5,000 deaths recorded so far. Around 3,200 of those have been police. The mission ends with 2,224 American soldiers killed, according to an AP tally, out of a total of some 3,500 foreign troop deaths.