1. Agence France-Presse. (2019). EU defends military reforms against US criticism. Voice of America. https://www.voanews.com/a/eu-defends-military-reforms-against-us-criticism-/4920447.html. Accessed 19 May 2019.
2. Allison, G. (2020). The new spheres of influence: Sharing the globe with other great powers. Foreign Affairs, 90(2), 30–40.
3. Ashford, E. (2017). Hegemonic blackmail: Entrapment in civil war intervention. Canadian Foreign Policy Journal, 23(3), 218–231.
4. Baldor, L. C. (2019). Officials: US to send about 1,000 more troops to Poland. Military Times. https://www.militarytimes.com/news/your-military/2019/06/12/officials-us-to-send-about-1000-more-troops-to-poland/. Accessed 15 June 2019.
5. BBC. (2017a). Trump worries NATO with “obsolete” comment. BBC. https://www.bbc.com/news/world-us-canada-38635181. Accessed 2 August 2019.