Dwindling coal exports could be a political headache for Putin, especially amid other bad news for the wartime economy, such as a downturn in manufacturing and warnings by Russian officials about inflation and high interest rates.

US President Donald Trump and Russia's leader Vladimir Putin have spoken for nearly an hour to negotiate solutions on Ukraine.

The U.S. president urged Russia’s leader to quickly end the war in Ukraine, according to a Kremlin briefing on the hourlong call.

The call with Vladimir Putin came as Ukrainian President Volodymyr Zelensky said publicly he wanted to discuss weapons supplies with President Trump.

The call marked the sixth publicly acknowledged conversation between the two leaders since Trump returned to office earlier this year.