U.S. Ambassador to Afghanistan Ryan Crocker discussed the attacks of 9/11, the ongoing fight to defeat the Taliban and why the U.S. needs to stay engaged in the fight there with NBC News' Atia Abawi.

"We are fighting the same adversary that gave al-Qaida the space and shelter to plan 9/11 -- and the Taliban haven't become kinder or gentler in the meantime," said Crocker. "They are still a formidable adversary and I have every expectation that if they were somehow to retake this country because we got tired of the fight, al-Qaida would be back in business in Afghanistan. I saw 9/11 once, I never want to see it another 9/11 again."

Click on the video above to watch the full interview.