• Summary
• EU leaders launch Ukraine's membership process
• Zelenskiy urges West to speed up heavy weapons deliveries
• Battle for Donbas twin cities reaches critical stage

KYIV, June 23 (Reuters) - Ukraine became a candidate to join the European Union on Thursday, a bold geopolitical step triggered by Russia's invasion that Kyiv and Brussels hailed as an "historic moment".

Starting on the long path to EU membership will be a huge boost to morale in the embattled country, as Russian assaults on two cities in the eastern Donbas region move toward a "fearsome climax", according to a Ukrainian government advisor. 

"Ukraine's future is in the EU," tweeted President Volodymyr Zelenskiy after the official announcement.

"A historic moment," European Council chief Charles Michel tweeted, adding: "Our future is together." read more

The approval of the Kyiv government's application by EU leaders meeting in Brussels will anger Russia as it struggles to impose its will on Ukraine. Moldova also became an official candidate on Thursday, signalling the bloc's intention to reach deep into the former Soviet Union.

Friday will mark four months since Russian President Vladimir Putin sent troops across the border in what he calls a "special military operation" partly necessitated by Western encroachment into what Russia considers its sphere of influence.

The conflict, which the West sees as an unjustified war of aggression by Russia, has killed thousands, displaced millions and destroyed cities, while the curtailment of food and energy exports has affected countries across the world.

Prime Minister Boris Johnson said Britain was willing to assist with demining operations off Ukraine's southern coast and was considering offering insurance to ships to move millions of tonnes of grain stuck in the country. read more

Russia has focused its campaign on southern and eastern Ukraine after its advance on the capital in the early stages of the conflict was thwarted by Ukrainian resistance.

The war of attrition in the Donbas - Ukraine's industrial heartland - is most critical in the twin cities of Sievierodonetsk and Lysychansk, which sit on opposite banks of the Siverskyi Donets River in Luhansk province.

The battle there is "entering a sort of fearsome climax", said Oleksiy Arestovych, an adviser to Zelenskiy.

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Russian forces were trying to encircle Ukrainian troops defending Lysychansk, senior Ukrainian defence official Oleksiy Gromov said in a briefing on Thursday.

Luhansk governor Serhiy Gaidai said separately that all Lysychansk was within reach of Russian fire and that Ukrainian troops there might retreat to new positions to avoid being trapped.