An attempt to include a former Soviet republic in a military alliance, of which Russia is not a part, would undoubtedly be seen as threatening and, if necessary, answered by military forces.
This is what Sergey Rogov, the then Russian president Boris Yeltsin's security policy adviser, said in an interview with SVT in 1996.
But the Baltic countries stood their ground and today all three are NATO members.
Watch the Baltics' journey from independence to a NATO member in the video above.