Federal officials are shutting down a Russian-owned compound on Maryland's Eastern Shore amid sweeping U.S. sanctions in response to election-related hacking.
President Barack Obama gave Russia until Friday at noon to leave the 45-acre property, which the Soviet government bought in 1972.
One of two Russian compounds that the U.S. plans to close is located in Centreville, Maryland, a State Department official confirmed to News4 Thursday afternoon. The other is in Glen Cove, New York.
Video shot from Chopper4 Thursday afternoon and again Friday morning shows a flurry of activity and multiple unmarked cars on the perimeter of the sprawling waterfront property in Centreville.
On Thursday, officials appeared to set up an antenna, plus lights at each entrance. A man in what looked to be a law enforcement boat appeared to watch the property by water.
White House officials said the facility is recreational but also used for intelligence activities.
Intelligence officials told NBC News the property was used for work to monitor the National Security Agency (NSA) headquarters in Fort Meade, Maryland, and another NSA building on Kent Island.
The second compound U.S. officials ordered Russia to vacate is in Long Island, New York.
Obama said Thursday that his administration is kicking out of the country 35 Russian diplomats working as intelligence operatives.
"All Americans should be alarmed by Russia's actions," he said in a statement. He added: "Such activities have consequences."
These 35 people work in the Russian Embassy in D.C. and the Russian Consulate in San Francisco, the State Department said. They are being declared "persona non grata" and will be given 72 hours to leave the country.
Trump released this statement Thursday evening: "It's time for our country to move on to bigger and better things. Nevertheless, in the interest of our country and its great people, I will meet with leaders on the intelligence community next week in order to be updated on the facts of this situation."
Russian officials have denied the Obama administration's accusation that the Russian government -- including President Vladimir Putin himself -- worked to influence the U.S. presidential election.
U.S. intelligence agencies concluded that Russia's goal was to help Donald Trump win -- an assessment Trump has dismissed as ridiculous.
The president-elect was asked on Wednesday about possible sanctions against Russia.
"I think we ought to get on with our lives," he said.
Stay with News4 and NBCWashington.com for more details on this developing story.