UPPER BROOKVILLE, N.Y. — Not long after the United States abruptly ordered all Russians to leave an estate that Moscow owns in Upper Brookville, Long Island, the village was recovering from the whirlwind that swept through it right before New Year’s Eve. As to who was there and what they were exactly doing remains a mystery, but a second new mansion on the site could be a culprit.

The estate, which features a circa-1918 mansion called Norwich House, was closed by the US government in the final days of December as new sanctions were imposed against Russia for hacking the Democratic National Committee during the US presidential election, according to the Obama White House, thus influencing votes. “These actions are unacceptable and will not be tolerated,” Obama’s statement read.

The US accused Russia of using two of their residential compounds, on Long Island and in Maryland, for “intelligence-related purposes.”

The Russians evicted from Upper Brookville in Oyster Bay Township did not dispute the accusation and left the site without fuss on Dec. 30, meeting a noon deadline. They reportedly drove off in six vehicles and were using the “retreat,” as the Russians bill the compound, during the holidays; a caretaker was also evicted. A Russian spokesman for the country’s United Nations mission told PassBlue that the estate was not a source of spying.

But there is an equally large house, built around five years ago, facing Norwich House, which acted as a dacha, or vacation residence, for people from the Russian mission to the United Nations. Completed in October 2013, it accommodates up to 30 people, with eight two-room suites and four one-room suites, a European-style ballroom with a spiral staircase, a big basement and 12 air-conditioning units on the roof, according to the architect, Peter Elkin. An outdoor barbecue pit was also installed.

The children of the diplomats, Elkin said in a phone interview, went there for summer camp, with their families living on the campus, too.

Were the buildings used for spying?

“I don’t know,” Elkin said, adding that halfway through the project, the Russians upgraded the compound to make it more “secure,” installing a gated entrance and cameras. He was also involved in renovating the 1918 mansion; the Russians themselves gutted and rebuilt the ground floor, kitchen and conservatory, replacing the old walls with Sheetrock and studs, rewiring the electricity and redoing the plumbing, all done with no building permit, apparently.

Elkin, who is based on Long Island, said that the contract for his work on the estate was signed by Vitaly Churkin, Russia’s ambassador to the UN. Elkin was known by the Russians for having worked on their apartment tower in the Bronx, where he designed a sports complex on site. The building’s top floor, he noted, was restricted and is “where the business goes on”: spying.

He said he enjoyed the design job and “working with a superpower.”

A longtime neighbor of the Norwich House compound, who preferred to remain anonymous, confirmed that children and adults showed up regularly during the summer and on weekends, notably on May Day.

Asked whether in her five-plus decades of living nearby she ever suspected the Russians of using the compound for espionage, she said, “Look, everybody spies on everybody.”

Yet there is no record of the second building on Nassau County land records, which provides details of the old mansion and upgrades. Elliot Conway, the mayor of Upper Brookville, said that he didn’t know anything about the buildings on the property, but that a building permit from 2009 was filed for construction of the new house.

The media attention on Norwich House, which is ensconced on 14 acres in this incorporated village, was at first riveted on a second Russian mansion on Long Island’s North Shore, in Glen Cove. That estate, named Killenworth by its original owner, George Dupont Pratt, in 1912, is also somewhat camouflaged by woods. It is located 20 minutes west of Upper Brookville, down the road from the Long Island Sound and about a half-hour drive to New York City.

Glen Cove, a more urbanized center than Upper Brookville, is where local, regional and global media — like British newspapers — flocked when the White House announced it was closing Russian “recreational” properties.

Confusion reigned among media and officials of the two Long Island towns because the US had pinpointed Killenworth, on 36 acres, as the mansion that would be off-limits to Russians who used it and lived there.

Conway apparently straightened out the problem, confirming through the State Department that it was Norwich House being shut on Long Island and not Killenworth.

“They were not happy to leave,” said Conway, who told PassBlue he watched the Russians drive away on Dec. 30 as he stood at the mansion’s gated entrance. “Who would? It’s the best village in the US.”

As to why the Obama administration picked Norwich House over Killenworth as part of its recent sanctions, a US State Department spokeswoman offered few details, other than to say: “The New York property is on Long Island and is 14 acres. It was purchased by the Soviet government in 1954. We’ll offer no other details beyond that.” (The US says 1954 but local records show it was bought in 1952.)

Elizabeth Kennedy Trudeau, the US spokeswoman, added: “Under U.S. law, the State Department’s Office of Foreign Missions can restrict access to such properties. The legal basis is the Foreign Missions Act (22 U.S.C. 4301).”

The entrance of Norwich House is off Mill River Road, a meandering stretch of old restored gatehouses, new mansions and Colonial-era houses in a main enclave of the fabled Gold Coast. The region was brought to power by major American capitalists — robber barons — more than 100 years ago.

Downtown Oyster Bay is minutes from Mill River Road; a low-key spot, it was made famous by another summer resident, Theodore Roosevelt, the US president from 1885 to 1919, until he died.

It’s hard to miss the Rough Rider’s spirit: a statue of him is parked near town offices, and an elementary school is named after him. His estate, Sagamore Hill, is outside town, in Cove Neck, built on a hill overlooking Oyster Bay Harbor. The estate is a National Park Service property.

Espionage, in fact, is an Oyster Bay legacy: Raynham Hall, on West Main Street, is the “home of George Washington’s intelligence operative Robert Townsend,” says the museum website. Townsend was part of Washington’s Culper Ring spy circle, organized during the British occupation of New York City in the Revolutionary War. The ring was so clandestine that it used invisible ink in publications to message its affairs.

Another less-famous but more recent resident was Marie Colvin, a journalist who covered the war in Syria for The Sunday Times (of London). Colvin grew up in Oyster Bay and was killed by Syrian government shelling in February 2012, making her one of the first journalists to die in the conflict.

On a Jan. 5 visit to Upper Brookville after the media circus left, the neighborhood was ominously quiet, as if recovering from the hangover of witnessing the eviction of Russians from what some residents say was a beloved retreat for the foreigners.

“It surprised the hell out of me,” said the longtime neighbor. She has lived near the compound since she was a child, and like most people in the vicinity, she said the Russian neighbors “never complained.”

A Russian who lived at the compound — most likely the caretaker — would bring over Stolichnaya vodka for Christmas, the woman said. One time, he asked what he should feed the deer roaming the property. (She suggested corn.)

Conway, the mayor, who has lived in the area for more than 60 years, said that many people were surprised to learn of the Russian presence but “not concerned that Russians were here.”  The estate is edged by a wooded hill, a golf course belonging to the Mill River Club and horse pastures of a neighbor in the back.

The 38-room mansion has a long pedigree but appears to have had only three owners: Frank C.B. Page, an executive for a machine-tools maker, E.W. Bliss, in Brooklyn, N.Y., who built the house and called it Elmhurst; Nathan L. Miller, a New York governor from 1921-1922, who installed an indoor swimming pool around 1938; and the Russians, who bought it in 1952.

The Bliss company was based in what is now called Dumbo in Brooklyn; besides metal plates, it manufactured torpedoes that the US deployed in the Spanish-American war.

Public records show that Jacob A. Malik bought the estate for the Union of Soviet Socialist Republics on Sept. 18, 1952, and was identified as the “resident representative of the USSR to the United Nations.” The record declares the property as “Exempt-Foreign Government.” Malik was the Soviet ambassador to the UN from 1948 to 1952 and from 1968 to 1976.

He was preceded as Russian ambassador to the UN by Andrei Gromyko, from 1946 to 1948, when the UN headquarters were temporarily located in Lake Success, a village in Nassau County on Long Island.

Gromyko, who became a potent foreign minister during the Cold War, acquired the nickname Mr. Nyet — Mr. No — for his prolific use of the veto on the UN Security Council.

In a further twist, Gromyko could have been the first Russian diplomat to taste the luxuries of Long Island’s North Shore, having rented a mansion in Woodbury from the Ogden Mills family while he worked at the UN.

Mills, who had inherited an oil and biscuit fortune, was President Hoover’s secretary of the treasury. The mansion was grand: 40 rooms on 640 acres.

At the much smaller Norwich House, the mansion is reachable by a long, curvy gated driveway. Aerial views show a tennis court, soccer field and garden. On Jan. 5, no one was in sight, though when a reporter photographed the entrance, a white sport-utility vehicle soon came down the driveway as the reporter drove off.

Local police referred questions about who was now guarding the estate to the State Department, who responded in an email: “The facility has been closed, Russian personnel have left, and entry or access to the property will be granted only with permission of the Department of State. The State Department will secure and maintain the property in keeping with our responsibilities.”

It is easy to understand the White House confusion over which Russian mansion on Long Island was getting the boot: Killenworth is the more famous and vastly larger, composed of nearly 27,000 square feet and featuring 18.5 bathrooms, an outdoor pool and a tennis court. (Norwich House has 11 bathrooms.)

Killenworth is supposedly where Russian VIPs relax when they come to New York, and where Churkin, the Russian ambassador to the UN, escapes on summer weekends from the city, as well as other upper-echelon from the delegation.

Churkin once told PassBlue that the house was too costly to heat and that no one would buy it because of the upkeep. Russia has been heavily sanctioned by Europe and the US for its aggressions in Ukraine, so its foreign ministry budget may have been slashed as a result.

On Jan. 5, the Killenworth mansion, partly visible from Dosoris Lane, was dark. It is maintained by Russian caretakers on site, said Lisa Travatello, a public-relations officer for the City of Glen Cove.

Like the Norwich House, the driveway’s gated entrance revealed little except for a minivan with diplomatic license plates, parked on the inside. Killenworth borders a YMCA, and from its parking lot a greenhouse on the estate can be glimpsed. Like some other vestiges of the Gatsby era on the Gold Coast, it was caved in, lost and forgotten.

Killenworth is assessed at $17 million, Travatello said, but because it is owned by the Russian government and has diplomatic privileges, no taxes are paid to a US government entity or municipality, Travatello said, adding, “When you go through the gates, you’re on Russian property.”

The estate pays utilities, however: a Glen Cove municipal office said the Russians pay $14,000 a year for their water at Killenworth, by check.

The assessed value of Norwich House is $9.3 million, said the mayor’s office in Upper Brookville, which is located in an old Tudor cottage on the grounds of the Planting Fields Arboretum State Historic Park.

As with Killenworth, the Russians pay no taxes on the Norwich House estate. Upper Brookville officials said they would reap an estimated $35,000 annually in taxes alone if the Russians were not exempt.

Churkin, the Russian ambassador, spoke to reporters at the UN on Dec. 30 to explain the Russian-Turkish brokered cease-fire in Syria — a war that has killed countless children, with the help of Russian bombing. At the briefing, Churkin was asked about the US seizure of the Long Island estate, saying it was “quite scandalous that they chose to go after our kids.”

They know full well, he added, that the “two facilities” — not specifying which ones — are used by Russian diplomats’ children during school holidays. “So here go their family values.”

As for the use of Norwich House by the Russians again, the Russian spokesman suggested they would wait and see, particularly as Donald Trump takes over the US presidency on Jan. 20.

Dulcie Leimbach

Dulcie Leimbach is a co-founder, with Barbara Crossette, of PassBlue. For PassBlue and other publications, Leimbach has reported from New York and overseas from West Africa (Burkina Faso and Mali) and from Europe (Scotland, Sicily, Vienna, Budapest, Kyiv, Armenia, Iceland and The Hague). She has provided commentary on the UN for BBC World Radio, ARD German TV and Radio, NHK’s English channel, Background Briefing with Ian Masters/KPFK Radio in Los Angeles and the Foreign Press Association.

Previously, she was an editor for the Coalition for the UN Convention Against Corruption; from 2008 to 2011, she was the publications director of the United Nations Association of the USA. Before UNA, Leimbach was an editor at The New York Times for more than 20 years, editing and writing for most sections of the paper, including the Magazine, Book Review and Op-Ed. She began her reporting career in small-town papers in San Diego, Calif., and Boulder, Colo., graduating to the Rocky Mountain News in Denver and then working at The Times. Leimbach has been a fellow at the CUNY Graduate Center’s Ralph Bunche Institute for International Studies as well as at Yaddo, the artists’ colony in Saratoga Springs, N.Y.; taught news reporting at Hofstra University; and guest-lectured at the Columbia University Graduate School of Journalism and the CUNY Journalism School. She graduated from the University of Colorado and has an M.F.A. in writing from Warren Wilson College in North Carolina. She lives in Brooklyn, N.Y.