Mr Putin also warned that any outside power intervening on Ukraine’s behalf would face an “instant” response.Neighbouring countries have reacted to the crisis.In the Baltic republic of Estonia, which borders Russia, Prime Minister Kaja Kallas said a number of Nato allies that shared borders with Russia had agreed to launch consultations under Nato’s Article 4. Under the defensive alliance’s treaty, Nato can be brought together if any member fears their independence or territory is under threat.