(Bloomberg) -- Ukrainian President Volodymyr Zelenskiy made a surprise visit to the UK, only his second confirmed trip outside the country since the war began, as Prime Minister Rishi Sunak announced more training for Ukrainian troops and new help for fighter jet pilots.

Zelenskiy arrived on a Royal Air Force plane before heading into London to meet Sunak in Downing Street and speaking to UK lawmakers in Parliament. He will also meet King Charles III and visit Ukrainian troops training in southwest England.

Addressing lawmakers in English in Westminster Hall, the centuries-old venue where Queen Elizabeth II laid in state after her death, Zelenskiy praised the UK for backing Ukraine from the very start of the war. “London has stood with Kyiv since day one,” he said, insisting that Russia was destined to lose.

“The United Kingdom is marching with us towards the most important victory of our lifetime. It will be a victory over the very idea of the war. After we win together, any aggressor, it doesn’t matter, big or small, will know what awaits him if he attacks international order,” Zelenskiy said.

Follow Ukraine’s Zelenskiy Address to UK Parliament: TOPLive

Speaking at prime minister’s questions before Zelenskiy’s address, Sunak confirmed that the UK would ramp up military assistance, including training for Ukrainian marines and for pilots on advanced combat aircraft.

“We will continue to support Ukraine to ensure a decisive military victory on the battlefield this year,” Sunak told MPs.

The trip to the UK comes after a visit to the US in December, when Zelenskiy met President Joe Biden and addressed Congress, and will likely be seen as a vote of gratitude to the UK for being one of Ukraine’s primary suppliers of military aid. 

UK forces trained 10,000 Ukrainian troops in 2022 and aims to assist at least 20,000 more this year, Sunak said in Parliament. Britain is also providing Challenger 2 tanks as part of a £2 billion ($2.4 billion) weapons and equipment package.

Zelenskiy previously addressed Britain’s Parliament via video link in March 2022, two weeks after the start of the invasion. He echoed World War II Prime Minister Winston Churchill, vowing that Ukrainians “will fight till the end at sea, in the air. We will continue fighting for our land, whatever the cost.” It drew him a standing ovation from lawmakers. 

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Zelenskiy’s arrival will boost Sunak, who has faced domestic criticism over a rocky start to his premiership and a lackluster cabinet reshuffle on Tuesday. It also shows that Sunak’s decision not to send fighter jets to Ukraine has not affected the relationship with Kyiv. Former Prime Minister Boris Johnson had urged Sunak to increase support by sending planes.

“It is a testament to the unbreakable friendship between our two countries and I am proud that we are expanding the training for Ukrainian forces to include jet pilots and marines, and ensure that Ukraine has a military able to defend its interests today and in to the future,” Sunak said in the House of Commons.”

He also pledged to continue support for the long-term, assuring Zelenskiy the UK would stand with it “for years to come,” and backed a call by Labour Party leader Keir Starmer for Russia to be held accountable for crimes committed in Ukraine.

“One of the things I discussed with President Zelenskiy this morning is our support for the work of the ICC where, thanks to the efforts of UK members, I’m hopeful we will see the first indictments very shortly,” Sunak said.

In Brussels, the European Union is holding a leaders’ summit starting Thursday where Ukraine is high on the agenda.

Russia is trying to advance in Ukraine’s eastern Donetsk region and has managed to gain some small areas there. Kyiv authorities expect Moscow to increase its offensive in southern and eastern regions. On Wednesday, Russia shelled Ukraine’s largest city of Kharkiv in northeastern Ukraine with missiles. 

“We are paying maximum attention to what the occupiers are preparing. And to what our warriors need to effectively resist – in all directions,” Zelenskiy said in his daily video address to the nation, before heading to the UK.

--With assistance from Daryna Krasnolutska.

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