Ukraine's prime minister said on Saturday Russian President Vladimir Putin aimed to destroy Ukraine as an independent country and said only NATO could defend the ex-Soviet republic from external aggression.
Kiev and its Western backers accuse Moscow of sending troops and tanks into eastern Ukraine in support of pro-Russian separatists battling Ukrainian forces in a conflict that has killed more than 3,000 people. Russia denies the accusations.
A fragile ceasefire negotiated by envoys from Ukraine, Russia, the separatists and Europe's OSCE security watchdog, has been in place in eastern Ukraine for more than a week and is broadly holding despite sporadic violations.
"We are still in a stage of war and the key aggressor is the Russian\ Federation ... Putin wants another frozen conflict (in eastern Ukraine)," Prime Minister Arseny Yatseniuk told a conference attended by European and Ukrainian lawmakers and business leaders.
Yatseniuk said Putin would not be content only with Crimea - annexed by Moscow in March - and with Ukraine's mainly Russian-speaking eastern region.
"His goal is to take all of Ukraine ... Russia is a threat to the global order and to the security of the whole of Europe," said Yatseniuk, who is known for his hawkish rhetoric.
Asked about future NATO membership, a red line for Russia, Yatseniuk said he realized the alliance was not ready now to admit Kiev, but added: "NATO in these particular circumstances is the only vehicle to protect Ukraine."
There is no prospect of the Atlantic alliance admitting Ukraine, a sprawling country of 45 million people between central Europe and Russia, but Kiev has stepped up cooperation with NATO in a range of areas and has pressed member states to sell it weapons to help defeat the separatists.
Russia 'bluffing' over sanctions
Yatseniuk also praised a new wave of economic sanctions imposed on Russia by the European Union and the United States and said they posed a major threat to the Russian economy.
"It is bluff (by Russia) to say it does not care about the sanctions," he said, noting that Russia relied heavily on its energy sector and some of the sanctions target its oil firms.
Western powers imposed new sanctions on Friday, tightening financial measures against Moscow in a move Putin called "a bit strange" in view of the ceasefire.
Yatseniuk defended his government's efforts, despite the conflict, to tackle rampant corruption and overhaul the creaking economy, adding: "It is very hard to attract investors when you have Russian tanks and artillery in your country."
Yatseniuk, whose centre-right People's Front party is expected to do well in a parliamentary election on Oct. 26, praised a decision on Friday to delay the implementation of a new trade pact with the European Union until the end of 2015.
Some have seen the decision to postpone the implementation of the deal as a diplomatic victory for Russia, which is opposed to closer economic ties between Kiev and the EU, but Yatseniuk said it would be good for Ukraine's own economy.
"We got a grace period. The EU opened its markets but Ukraine is still protected, so for Ukraine this is not a bad deal," he said.