A Kremlin official warned Friday that any release of transcripts of phone calls between Donald Trump and Russian President Vladimir Putin could exacerbate problems that already exist between the nations.

“We would like to hope that things won’t come to such situations in our bilateral relations, which already have plenty of quite serious problems,” Kremlin spokesperson Dmitry Peskov told reporters Friday in a conference call, Bloomberg reported.

“This is a rather unusual practice,” Peskov said. “As a rule, the materials from conversations on the level of the head of state are considered secret or top secret.”

Peskov was responding to a question about the Kremlin’s reaction to the White House decision to release a summary of the controversial July 25 call between Trump and Ukrainian President Volodymyr Zelenskiy. Trump’s repeated requests in the call to Zelensky to launch an investigation into his political rival Joe Biden and his son are now the target of an impeachment inquiry.

Despite his warning about U.S. actions, Peskov also said Moscow would consider exposing the contents of phone calls with Trump on a case-by-case basis, according to Bloomberg. “No one has turned to us with such requests,” he added.

Russian Foreign Minister Sergei Lavrov also said Friday that sharing Trump-Putin conversations would be “indecent.”

“As for transcripts of phone conversations, my mother when bringing me up said that reading other people’s letters is inappropriate,” Lavrov told reporters at the United Nations, Agence France-Presse reported.

“It is indecent,” he said. “For two people elected by their nations to be at the helm, there are diplomatic manners that suppose a certain level of confidentiality.”

Trump has been accused of being exceptionally secretive about face-to-face conversations with Putin. On at least one occasion in Hamburg, Germany, in 2017, Trump took possession of the notes taken by his own interpreter, whom he instructed not to reveal what was discussed to other administration officials, sources told The Washington Post. By early this year, officials said there was no detailed record of Trump’s face-to-face interactions with Putin at five locations since Trump became president.

The Washington Post reported Friday that access was also limited to comments Trump made to Kremlin officials in 2017 that Russian interference in U.S. elections didn’t bother him because America did the same elsewhere.

Former special counsel Robert Mueller found during his investigation that the Russian government “interfered in the 2016 presidential election in a sweeping and systematic fashion” in an effort to secure a victory for Trump.