The Kremlin spokesman Dmitry Peskov has expressed surprise that the private phone calls of President Donald Trump have been made available for public consumption in contravention of international practice. “The materials related to conversations between heads of states are usually classified according to normal international practice,” he told reporters.

Trump’s notorious phone call to his Ukrainian counterpart Volodymyr Zelensky was recently released to Congress. The release of the transcript led House Speaker Nancy Pelosi to launch a formal impeachment inquiry into the president’s conduct on Tuesday.

The fact that the U.S. government has reluctantly publicized the confidential conversation between two currently serving presidents is totally unprecedented in the history of international politics.

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The Kremlin is understandably anxious that private telephone conversations between Trump and Russian President Vladimir Putin might be disclosed. Trump and Putin have long raised eyebrows with their unusual relationship. Trump, recently even, pushed for Putin to attend next year’s G7 Summit. Russia was expelled from the then-G8 after its invasion of Crimea.