Russian foreign minister Sergey Lavrov is threatening "counter actions" against the United States over a pair of Russian diplomatic compounds seized by the United States last year.
A month after US President Donald Trump's election victory, then-president Barack Obama seized the Cold War-era recreational estates and expelled 35 Russian officials.
Mr Trump and Russian President Vladimir Putin discussed the issue at the G-20 summit in Germany last week.
After meetings at European Union headquarters on Tuesday, Mr Lavrov said Moscow was "still hopeful that the US, as a proponent of the rule of law, will finally respect the international obligations".
He continued: "If this is not the case, if Washington decides not to solve this issue, we will have to take counter actions."
Mr Lavrov refused to elaborate.