Ambassador : Russian aggression against Ukraine has been challenge to peace . Petro Poroshenko : And while Russian aggression is clearly the catalyst , any changes should not be seen as simply directed at a single country , but as part of generally much-needed changes . Ukraine has disregarded provisions of NATO . Time for Russia to rethink relationship with Budapest Memorandum , he says .
Ambassador : Russian aggression against Ukraine has been challenge to peace . Petro Poroshenko : Ukraine has disregarded provisions of NATO . Time for Russia to rethink relationship with Budapest Memorandum , he says .