As the airlift continues at Hamid Karzai International Airport, questions continue to emerge on the withdrawal by America and its allies from what is described as the "forever war". Twenty years after the U.S.-led invasion in 2001, and as criticism builds even in Western capitals, what's next in this humanitarian crisis? And what will happen to the millions of people left behind?

This opinion piece is by Zhao Minghao from Fudan University's Institute of International Studies.