The war in Afghanistan turns 11 years old (CBS News) KABUL, Afghanistan - Eleven years ago this weekend, the first U.S. soldiers entered Afghanistan. As many are now leaving the longest war in American history, two-thirds of those in uniform defending Afghanistan are Afghans -- a force of over 350,000. The question is: Can they hold off the Taliban? The U.S. troop surge succeeded in taking back big chunks of territory from the Taliban, but with the last of those 33,000 troops gone, it's largely down to Afghan security forces to hold on. Lt. Col. Leroy Barker helps oversee a checkpoint where, just beyond, Taliban fighters persist. 2 U.S. troops, 2 Afghan policemen killed in fighting Panetta says Karzai should thank allied forces U.S. suspects Haqqani tie to Afghan insider attacks There's been operation after operation, but clearing that is not as easy as it looks," Barker said. What used to be a U.S. base, is now a checkpoint manned by Afghan police protecting a vital road that's under constant threat from the Taliban. But it still receives plenty of hands-on U.S. support. U.S. military officials call training Afghan security forces to stand alone, while still providing security backup "mentoring." That includes teaching them to find homemade bombs - the biggest threat here. And there has been progress. Afghan forces now take the lead role in defending against attacks - like the Taliban assault on the U.S. Embassy in Kabul. NATO officials say Afghans participate in 90 percent of military operations. Analyst Michael O'Hanlon of the Brookings Institute says that's cause for optimism. "If you give them a gun, and tell them where the enemy is, and maybe ask them to cover for each other as they move from rock to rock or building to building -- just like the Taliban is a bunch of fighters, Afghans are pretty good with a gun," O'Hanlon said. Yet Afghan forces remain vulnerable. Last month, they failed to stop a suicide bomber from killing 12 foreigners in Kabul. Eleven years after U.S. troops and allies toppled the Taliban, Afghan forces are still unable to hold their own against a determined enemy.