Volodymyr Zelenskiy, who won 73% of the vote last month, justified his contentious decision on the grounds that the legislature, controlled by allies of the man he defeated, is riddled with self-enrichment.
Elections to the Supreme Rada were scheduled for Oct. 27, which raised the prospect of Zelenskiy struggling to enact his agenda in the face of a hostile parliament over his first few months in power.
A snap parliamentary election will be held within two months of his signing a formal dissolution decree.
Zelenskiy, a comedian who played the role of a Ukrainian president on a popular TV show for years, is gambling that his popularity will see the next parliament dominated by supporters of his agenda to reform Ukraine and steer a new path with Russia.
Zelenskiy said Ukrainian politics for the past quarter-century created "opportunities for kickbacks, money laundering and corruption."
Zelenskiy's efforts follow repeated attempts by the majority in the current parliament to stymie his campaign promise for a new election.
Since last month's election, Zelenskiy's opponents in the Rada sought to put off the inauguration close to the May 27 deadline by which the parliament can be dissolved.
And in a dramatic move last week, the Rada announced the collapse of the ruling parliamentary coalition. According to parliamentary rules, the chamber can't be dissolved for 30 days after the governing coalition has been disbanded.
Zelenskiy's supporters argue that the Rada's actions are legally void because the coalition had long ceased to exist and that the Ukrainian Constitution, unlike the Rada regulations, doesn't contain such a rule.
Volodymyr Fesenko, head of the Kiev-based think-tank Penta, said Zelenskiy's announcement shows "political will for radical change."
"The legally dubious decision to disband parliament will certainly be contested in court but Zelenskiy has shown that it is going to be him who will lay down the agenda and that he will dominate the political landscape," he said.
Zelenskiy's landslide victory reflected Ukrainians' exhaustion with widespread corruption and the country's political elite. Before disbanding parliament, the 41-year-old Zelenskiy upended other Ukrainian political traditions on inauguration day.
He ditched the idea of a traditional motorcade to his inauguration, walking to the parliament in Kiev through a park packed with people. Flanked by four bodyguards, the beaming president-elect gave high-fives to some spectators, even stopping to take a selfie with one of them.
At the end of his swearing-in ceremony, Zelenskiy asked the Supreme Rada to adopt a bill against illegal enrichment and support his motions to fire the country's defense minister, the head of the Ukrainian Security Service (SBU) and the Prosecutor General. All are allies of Zelenskiy's predecessor, Petro Poroshenko.
That's when he dropped his bombshell about dissolving parliament. Zelenskiy told lawmakers they only have a few weeks to support his motions, as that's as long as the current parliament has.
Two of the three officials he has asked to leave, Defense Minister Stepan Poltorak and SBU chief Vasyl Grytsak, promptly handed in their resignations.
Later, Prime Minister Volodymyr Groysman said he would resign Wednesday. That move would be largely symbolic because it would have to be approved by the parliament. If accepted, he would remain as acting prime minister until after the elections.
Zelenskiy also told the Rada that the main goal for the presidency is to bring peace to eastern Ukraine, where government troops have been fighting Russia-backed separatists for five years in a conflict that has left at least 13,000 dead.
"I'm ready to do everything so that our heroes don't die there," he said. "It wasn't us who started that war. But we need to be the one to finish it."
The new president wrapped up his speech at parliament by referring to his career as a comedian.
"Throughout all of my life, I tried to do everything to make Ukrainians laugh," he said with a smile. "In the next five years I will do everything, Ukrainians, so that you don't cry."
Nataliya Vasilyeva reported from Moscow. Vladimir Isachenkov in Moscow and Yuras Karmanau in Minsk, Belarus, contributed to this report.
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