The invitation to the small Balkan country comes with the West at loggerheads with Moscow over a host of issues, as NATO has responded to the Ukraine crisis with a military upgrade to reassure nervous ex-Soviet states they need not fear a more assertive Russia
The alliance was reacting to a warning from a London-based think tank about the risks from a sharp increase in Russian and NATO war games since the conflict between the Ukrainian government and pro-Russian separatists flared up in April last year.
Ukrainian President Petro Poroshenko said Wednesday that Russia had withdrawn most of the troops it allegedly sent across the border to back a bloody pro-Kremlin uprising
Obama was speaking in Estonia, one of three ex-Soviet Baltic states bordering Russia that fear separatist rebellion in eastern Ukraine could herald problems for them
Russian President Vladimir Putin on Wednesday ordered a snap check of the battle-readiness of the armed forces in the western and central military districts