https://www.brookings.edu/articles/why-do-us-presidents-like-military-assistance/
https://rusi.org/explore-our-research/publications/commentary/why-did-afghan-army-evaporate
https://www.brookings.edu/blog/order-from-chaos/2020/04/06/stretching-the-international-order-to-its-breaking-point/?utm_campaign=Brookings%20Brief&utm_source=hs_email&utm_medium=email&utm_content=85914360
http://dip21.bundestag.de/dip21/btd/19/072/1907200.pdf