
https://www.brookings.edu/blog/order-from-chaos/2021/03/30/the-us-military-must-plan-for-encounters-with-private-military-companies/?utm_campaign=Brookings%20Brief&utm_medium=email&utm_content=118778216&utm_source=hs_email

https://www.nato.int/nato_static_fl2014/assets/pdf/pdf_2018_03/20180315_SG_AnnualReport_en.pdf

https://www.crisisgroup.org/crisis-crunching-what-crisiswatch-says-about-todays-conflicts-and-tomorrows?utm_source=Sign+Up+to+Crisis+Group%27s+Email+Updates&utm_campaign=99397fafcc-EMAIL_CAMPAIGN_2020_02_26_03_37&utm_medium=email&utm_term=0_1dab8c11ea-99397fafcc-359810589