Matthew Bracken (@Matt_Bracken)

This is Jack F. Matlock Jr., US Ambassador to the Soviet Union from 1987-1991, warning in 1997 that NATO expansion was "the most profound strategic blunder, [encouraging] a chain of events that could produce the most serious security threat since the Soviet Union collapsed." (Incidentally, Matlock was in Moscow in 1962 during the Cuban Missile Crisis with the State Dept at the embassy.)