Kiev on Thursday accused Russia of flagrantly threatening Ukraine with destruction ahead of President Volodymyr Zelensky's meeting with the leaders of France and Germany.
Concern is mounting that the long-simmering conflict in east Ukraine could spiral back into wider fighting after reports of major Russian troop movements and an intensification of clashes with Moscow-backed separatists.
The troop build-up along Ukraine's northern and eastern borders, as well as on the Crimean peninsula annexed by Moscow in 2014, comes amid a spike in violence along the front line between Russian-backed separatists and Ukrainian forces in the east of the country.
Zelensky is expected to travel to Paris on Friday to discuss the rising tensions with French President Emmanuel Macron.
The two leaders will be joined by German Chancellor Angela Merkel by video link, Macron's office said.
Ahead of the trip Zelensky urged NATO and the European Union to speed up Ukaine's membership process.
"We cannot stay indefinitely in the EU and NATO waiting room," the Ukrainian leader told the French daily Le Figaro.
"The time has come to step up a gear, to invite us to join the EU and NATO," he added, denouncing Russia's "violent aggression" against his country, in comments run on the newspaper's French language website.
- 'Unwavering support' -
The foreign ministers of EU members Estonia, Latvia and Lithuania arrived in Kiev on Thursday and European Council President Charles Michel spoke with the Ukrainian leader in a show of support.
Speaking alongside the visiting diplomats, Ukraine's Foreign Minister Dmytro Kuleba told reporters that rhetoric in Moscow had reached a fever pitch with pundits and officials issuing "dehumanising" statements aimed at intimidating Kiev.
"They are openly threatening Ukraine with war and the destruction of Ukrainian statehood," Kuleba said.
"The red line of Ukraine is the state border. If Russia crosses the red line, then it will have to suffer," Kuleba said in English.
Lithuanian Foreign Minister Gabrielius Landsbergis told reporters: "Ukraine will never be on its own."
The United States has reiterated its backing and on Thursday European Council President Michel "conveyed the EU's unwavering support" in phone talks with Zelensky, according to a readout of the call.
The foreign ministers of the EU will discuss Ukraine on Monday, Brussels said.
- 'Army is ready' -
On Friday, Macron will receive Zelensky for lunch in Paris, the Elysee said.
"It's an important meeting," the 43-year-old Ukrainian leader said after a meeting of the country's security council. He said the situation in the east was "under control."
"The army is ready, that's the most important thing," he added.
Together with Russia, France, Germany and Ukraine form the Normandy format of countries that have sought and failed to resolve the conflict since 2015.
On Wednesday, US President Joe Biden and Merkel agreed to call on Russia to reduce its troops on the border with Ukraine.
Russia dismissed the pressure.
Russian foreign ministry spokeswoman Maria Zakharova said that Western countries including Germany and France should "stop participating in the propaganda campaign surrounding Russian activity on Russian territory that does not threaten anybody".
- 'Reliable friends' -
Kuleba's warning on Russia came after international observers to the conflict said late Wednesday that there had been a dramatic increase in recent violations that was hindering their work.
"The number of violations recorded over the past two weeks has reached its highest level this year," monitors from the Organization for Security and Co-operation in Europe said in a statement.
An uptick in fighting since the start of the year has seen Moscow and Kiev blame each other for the rise in violence between government forces and separatists in eastern Ukraine.
Ukraine says the spate of clashes has cost the lives of nearly 30 Ukrainian servicemen and left at least another 68 wounded since January.
Kiev warned this week that 28,000 separatist fighters and more than 2,000 Russian military instructors and advisers are currently stationed in eastern Ukraine, while nearly 33,000 soldiers are deployed in Crimea.
Russia's defence ministry, however, said those troops were merely responding to "threatening" NATO actions by participating in military drills that would conclude in three weeks.
The renewed fighting has left in tatters a ceasefire brokered last July that had brought relative calm to the conflict.
"We are not afraid. Ukraine itself is strong enough and has reliable friends to defend its statehood," Kuleba said.