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.