The Kremlin warned on July 14 that it would reject any preconditions for the return of Russian diplomatic property seized by the United States.
The warning was in response to comments made on CNN by Sebastian Gorka, an adviser to U.S. President Donald Trump, that linked the compounds' return to Russia's adherence to a recent U.S-Russian cease-fire deal in southwest Syria.
"Return of the diplomatic property to Russia must not depend on any conditions," Kremlin spokesman Dmitry Peskov said. "This totally contradicts international law."
In December, then-President Barack Obama ordered the seizure of Russian diplomatic compounds in New York and Maryland and the expulsion of 35 Russian diplomats he said were spies, in a series of measures aimed at punishing Russia for allegedly interfering in the 2016 presidential election.
Russian President Vladimir Putin decided not to immediately retaliate over the expulsions and property seizure, saying he would wait to see what the Trump administration would do.
But Peskov and the Russian Foreign Ministry said the Kremlin is running out of patience and will retaliate by expelling U.S. diplomats and seizing American property in Russia unless an agreement to return the seized compounds comes out of high-level talks due to resume on July 17.
Based on reporting by Reuters, AP, and Interfax