- Newly Declassified Documents: Gorbachev Told NATO Wouldn't Move Past East German Border - Dave Majumdar, National Interest, December 12, 2017
- NATO Expansion: What Gorbachev Heard - National Security Archive, December 12, 2017
Member states of NATO, shows new members and dates, starting from 12 March 1999, Czech Republic, Hungary, Poland; more in 2004, including Bulgaria and Romania.
- Bulgaria BEZMER and adjacent regions GUIDE for American military, p. 19, wayback machine, archived 27 February, 2009
- US troops deploy to Bulgaria as part of NATO operation to support Eastern European allies -CNN, February 17. 2017
- US Soldiers in Bulgaria, Romania deter aggression, assure allies, By David Vergun, Army News Service, September 26, 2017
- Seabees Break Ground on Maritime Operations Center in Ukraine, By Mass Communication Specialist 1st Class Brannon Deugan Naval Mobile Construction Battalion (NMCB) 1 Public Affairs, 7 August, 2017