If Putin does, indeed, invade Estonia—on whatever pretext—NATO (including the US) would have no choice but to come to its defense, militarily. That is because Estonia joined NATO about 10 years ago.
I wonder if President Enrique Peña Nieto of Mexico feels that Mexican nationals are threated in California? Would Obama help defend California’s sovereignty if Mexico took over? Would many of the undocumented Mexicans rally behind Nieto or would they be heading for another State border to cross into the remaining United States?