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Russian ambassador Sergey Kislyak told BuzzFeed News that Russia is talking with the Trump administration "each and every day" about restoring two compounds seized by the U.S. under former President Barack Obama. "We insist that [the property] needs to be returned," Kislyak said. "It's a violation of the Vienna Convention. It belongs to Russia. … It was seized unlawfully."

The properties, in New York and Maryland, were seized in December when Obama expelled 35 Russian "intelligence operatives" following early reports that the Kremlin had tried to influence the U.S. presidential election. The property is used for "recreation for embassy and U.N. diplomats," BuzzFeed News writes. "But for decades, U.S. officials have suspected that it's also been used for espionage based on information from aerial surveillance."

The optics of turning the compounds back to the Russians are not good for the Trump administration, especially amid mounting allegations about the Trump campaign's possible collusion with Kremlin operatives. "Returning the compounds to Russian control is unjustifiable," a bipartisan group of senators told the Trump administration in a letter sent Wednesday.

Russia, though, has threatened to give American diplomatic properties the same treatment if immunity is not restored.