Ukrainian President Volodymyr Zelensky paid a surprise visit to the U.K. on Wednesday, the first leg of an unannounced diplomatic tour of European nations.

Prime Minister Rishi Sunak received Zelensky after he landed aboard a U.K. Royal Air Force C-17 transport plane at Stansted Airport, north of London. Sunak posted a photo of the pair embracing on the runway.

He then went to Buckingham Palace to meet King Charles III.

 "We've all been worried about you and thinking about your country for so long, I can't tell you," the British monarch said.

Zelensky delivered a speech to the joint houses of the British parliament in only his second international travel since Russia's invasion of Ukraine nearly a year ago, making a direct call for more heavy equipment, especially fighter jets.

"London has stood with Kyiv since day one," he said.

Zelensky gave the Speaker of the House of Commons, Lindsay Hoyle, the helmet of a Ukrainian fighter pilot, signed with the message: "We have freedom. Give us wings to protect it."

Zelensky's speech was directly aimed at Sunak and the Cabinet members who stood in front of him in the historic surroundings of Westminster Hall.

He thanked the British prime minister for announcing earlier that the U.K. will start training Ukrainian pilots on NATO-standard combat jets. He also mentioned former Prime Minister Boris Johnson, who was an early and ardent supporter.

Zelensky arrived in the U.K. at a time when Kyiv is pleading with the West to send more arms and military aid to oppose Russian advances.

On Wednesday, he also met with Ukrainian troops being trained by British forces, telling a press conference that his top objective on the battlefield is for Ukraine to receive more weaponry.

Zelensky's trip to London is just his second outside of Russia since Russia invaded Ukraine nearly a year ago, following a trip to Washington DC in December. The trip comes at a time when Zelensky has been desperately seeking military assistance from Western friends, as Ukrainian officials warn that Moscow is planning a spring onslaught.

Britain stated on Wednesday that it would provide additional military weapons to Kyiv to help repel a potential Russian spring onslaught. Sunak stated that the U.K. would provide more training to Ukrainian fighter pilots and marines, as well as a long-term investment in Ukraine's military.

Sunak's official spokesman stated on Wednesday that the U.K. is "actively" discussing sending British jets to Ukraine.