UPDATE 1-'This is a victory': smiling Zelenskiy promises EU membership, Russia defeat

(Adds quotes from Ukrainian President, chief of staff, background)

June 23 (Reuters) - President Volodymyr Zelenskiy on Thursday declared the EU's move to accept Ukraine as a candidate for accession as a victory and promised not to rest until Russia's defeat and full membership had been secured.

European Union leaders formally accepted Ukraine as a candidate to join the 27-nation bloc, a bold geopolitical move hailed by Ukraine and the EU itself as an historic moment.

"This is a victory," a smiling Zelenskiy said in a brief video posted to his Instagram channel, noting Ukraine had waited 30 years for this moment.

"We can defeat the enemy, rebuild Ukraine, join the EU, and then we can rest," he said in a low voice.

"Or perhaps we won't rest at all - our children would take offence. But without any doubt, we will win."

Andriy Yermak, Zelenskiy's chief of staff, said Kyiv would quickly implement the plan needed for accession talks to begin.

"Ukraine will be in the EU," he tweeted. (Reporting by David Ljunggren and Ronald Popeski; Editing by Mark Porter and Sandra Maler)