A Russian compound, which was ordered to be closed and vacated, is seen on Long Island, New York, on December 30, 2016.

Updated at 11:34 a.m. ET

Russian Foreign Minister Sergei Lavrov says his government is considering “specific measures” against the U.S. over its refusal to hand over two compounds seized last year by the Obama administration.

It is “simply shameful for such a great country as the United States, a champion of international law, to leave the situation in such a state of suspended animation,” Lavrov told Russian media. He did not elaborate upon what steps Russia would take.

Earlier, an unnamed foreign ministry official told Izvestia, the Russian newspaper, that up to 30 U.S. diplomats may be expelled from the country if the Trump administration doesn’t return the compounds in Maryland and New York. Thomas Shannon, the U.S. undersecretary of state, and Sergey Ryabkov, the Russian deputy prime minister, are expected next week to discuss the issue.

“If the compromise is not found there, we will have to take such measures,” the official told Izvestiya.

Russian officials had hoped there would be a breakthrough on the issue last week when President Trump met with Vladimir Putin, his Russian counterpart, on the sidelines of the G20 summit meeting in Hamburg, Germany. But though there was momentum on issues such as a ceasefire in the Syrian civil war, the issue of the compounds remained unresolved.