Ukraine troops clashed with around 30 armed men at Kramatorsk airfield in the first Ukrainian military action against a pro-Russia uprising in the east of the country.
Ukraine's acting president Oleksander Turchinov said the airfield had been retaken from pro-Russia separatists in what ITV News understands was a relatively peaceful manner.
ITV News Europe Correspondent Emma Murphy reports:
The pro-Russians barricaded the main gate with tires and pallets as they faced off with Ukrainian guards who were flown in.
It came after Turchinov announced an "anti-terrorist operation" against those who had seized control of numerous buildings in at least nine cities in eastern Ukraine.
President Vladimir Putin said Russia expects a "clear condemnation" from the international community over what he described as "Kiev's anti-constitutional action in eastern Ukraine."
However, following the move the White House said Ukraine's government has the "responsibility to provide law and order" in the region.
Foreign Secretary William Hague said tonight that Russia has made a "grave miscalculation" if it believes it can permanently destabilise Ukraine "without serious long-term consequences."
UN Secretary-General Ban Ki-moon voiced his alarm over the crisis in a phone call with Putin, stressing to the president the "need for everyone to work to de-escalate the situation."