Ukrainian President Volodymyr Zelenskyy arrived in the US on Thursday, ahead of his meeting with US President Donald Trump.

Trump is redoubling his efforts to end the war in Ukraine, announcing a second meeting with Russia's Vladimir Putin one day before sitting down with Zelenskyy at the White House.

Trump's announcement came shortly after finishing a call with Putin on Thursday. A date has not been set, but Trump said the meeting would take place in Budapest, Hungary.

“I believe great progress was made with today’s telephone conversation,” Trump wrote on social media.

Trump and Putin previously met in Alaska in August, which did not produce a diplomatic breakthrough, a source of frustration for the US leader who had expected that his longstanding relationship with Putin could pave the way to resolving a conflict that began nearly four years ago.

Yuri Ushakov, Putin’s foreign affairs adviser, said the Russian president initiated the call, which he described as “very frank and trusting." He said Putin emphasized to Trump that selling long-range Tomahawk missiles to Ukraine, something the US president has publicly discussed, would “inflict significant damage to the relations between our countries."

Trump was already scheduled to meet Friday with Zelenskyy, who has been seeking weapons that would allow Ukrainian forces to strike deeper into Russian territory. Zelenskyy has argued such strikes would help compel Putin to take Trump’s calls for direct negotiations to end the war more seriously.