Ukrainian President Volodymyr Zelenskyy has made pitches to allies around the world, but rarely in person. On Thursday, has went on a surprise visit to London to repeat his demands for fighter jets to use in his country's fight against Russian forces.

Zelenskyy made only his second trip abroad since the invasion began almost a year ago. He pushed Prime Minister Rishi Sunak for more weapons, as he did with Sunak's predecessors. He added to the pressure in an address before Parliament.

Zelenskyy said, "I appeal to you, and the world, with the simple and yet most important words: Combat aircraft for Ukraine. Wings for freedom."

Sunak said British pilots will train their Ukrainian counterparts on how to fly NATO combat aircraft. However, he has for now pushed back against Zelenskyy's request to send jets.

Sunak said, "Nothing is off the table. And that's because we're determined to ensure that, ultimately, the president and his people can be victorious against Russian aggression."

A spokesperson said Sunak has asked his defense secretary to look into whether the government can provide jets over the "long term."

Russian diplomats warned that such deliveries would have "military and political consequences for the European continent and the entire world."

However, Zelenskyy is pressing ahead. He has traveled to Paris to meet with French President Emmanuel Macron and German Chancellor Olaf Scholz.