• After nearly two decades of war, more than 6,000 American lives lost, over 100,000 Afghans killed and more than $2 trillion spent by the U.S., the speed of the Taliban takeover of Afghanistan has shocked the world.
  
• U.S. defense officials reportedly expected Afghanistan’s capital, Kabul, to fall in 90 days. It took less than 10 days.
  
• Among the key causes, analysts say, are intelligence failures, a more powerful Taliban, corruption, money, cultural differences and willpower.
  

DUBAI, United Arab Emirates — The world was shocked this week by horrifying scenes of desperate Afghans swarming the tarmac at Kabul’s international airport, grasping at their last chance to escape a country now completely overrun by the Taliban.

After nearly two decades of war, more than 6,000 American lives lost, over 100,000 Afghans killed and more than $2 trillion spent by the U.S., the outlook for the country’s future was still grim, with regional experts assuming the Taliban would ultimately come to control most of Afghanistan once again.

But few expected a takeover this swift, with so little resistance from the Afghan government and Afghan National Army, the latter of which was funded and trained with $89 billion from the U.S. taxpayer.

“While the end result and bloodletting once we left was never in doubt, the speed of collapse is unreal,” one former intelligence official and U.S. Marine who served in Afghanistan told CNBC, requesting anonymity due to professional restrictions.