A top security official has been accused of revealing potential U.S. policy changes to Moscow before the official inauguration of U.S. President Donald Trump.

U.S. security adviser Michael Flynn allegedly discussed anti-Russia sanctions with Sergei Kislyak, Moscow’s ambassador to the United States, before President Trump took office.

Nine former and current government sources told The Washington Post newspaper that conversations between the officials had “explicitly” mentioned ongoing U.S. sanctions, despite official White House denials.

Some raised concerns that the talks could have led Moscow to believe that sanctions put in place by President Barack Obama would be lifted under the new administration.

Two sources told the newspaper that Flynn had urged Russian officials not to overreact to Obama’s decision to expel Russian diplomats from the country in December 2016. The former president made the move after accusing the Kremlin of interfering in the U.S. elections. President Putin refused to retaliate and instead invited the children of U.S. diplomats in Russia to spend the New Years’ holidays at the Kremlin.