It was in August 2014 that the real danger began, and that we heard the first warnings of war. 

That month, unmarked Russian troops covertly invaded eastern Ukraine, where the separatist conflict had grown out of its control. 

The Russian air force began harassing the neighboring Baltic states of Estonia, Latvia, and Lithuania, which are members of NATO. 

The US pledged that it would uphold its commitment to defend those countries as if they were American soil, and later staged military exercises a few hundred yards from Russia's border.

Both sides came to believe that the other had more drastic intentions.