warsaw lithuania say grow rift eastern western european union state issue migration pose threat bloc time increase russian military assertiveness frictions ex-communist state europe east wealthy west increase since 2015 migration crisis britain decision leave bloc leaders try quell popular disenchantment eu nationalist politicians poland hungary call sweep reform bring power back member state expense brussels bureaucracy refuse take part efforts relocate migrants middle east believe worry lithuanian foreign minister linas linkevicius tell reuters sideline security conference warsaw ask polish hungarian assertiveness within eu would like see cohesion say know gain happy cohesion linkevicius say add refer russia take seriously help would like divide east west lithuania alongside poland particularly worry russia since moscow annex crimean peninsula ukraine 2014. nato seek reassure ally region send troop baltics poland black sea set network nato outposts hold exercise prepare rapid response force western officials express concern part baltic state large ethnic russian minorities could seize moscow much russia take control crimea linkevicius say good relations eu powerhouses germany france within eu crucial ability help militarily poland particular see tie paris berlin deteriorate since 2015 conservative law justice pis party take power issue military procurement wartime reparations eu single market rule lithuania say east-west schism within eu benefit russia