Inside a Bethesda elementary school this month, an Army official representing a group of U.S. intelligence agencies stood before 100 residents and issued a curt edict: Don’t ask for specifics about the spies poised to occupy your neighborhood.

“I really can’t say who’s coming to the facility,” Jared Olsen, a program manager with the Army Corps of Engineers, told the audience. “Let’s take that question off the table. Let’s just say it’s ‘Agencies very involved in protecting the United States, you all, and the rest of the citizens of the United States.’ ”

The residents — among them the Food and Drug Administration’s chief scientist and his wife, who is an assistant secretary of the Department of Health and Human Services, and a retired CIA researcher — weren’t pleased. But in Washington, there is bound to be some mystery and frustration when your neighbor happens to be an intelligence agency.

The neighbors are fighting the Army Corps’s design for the “Intelligence Community Campus — Bethesda,” which includes a parking garage that they fear will loom over the Potomac River and national historic parkland and require the felling of many trees.

Penelope Doolittle, 82, a retired longtime CIA researcher of Russian politics who lives behind the property in a neighborhood near the District line, said she was caught off guard by plans that she says were announced at the eleventh hour.

“The whole thing has been very dishonest. They just thought, ‘We’ll put up a garage back here, and nobody will complain.’ That’s the way they’ve behaved. They want to see what they can get away with,” said Doolittle, who worries about views from the planned garage of her home’s front deck, where she eats breakfast and watches birds. “If it’s a highly secure thing, they could have perimeter lights and all kinds of electronic stuff. You could be very paranoid. I don’t sense that we have much recourse.”

The Bethesda battle is like other fights in the Washington suburbs: Various branches of the federal government expand often in the name of national security, and local communities feel powerless to protect the sanctity of their turf.

In Alexandria, local and federal officials fear that traffic flow will be wrecked by the relocation of more than 6,000 defense workers to a Mark Center complex along Interstate 395. The location, according to a recent Pentagon report, was selected based on traffic counts conducted on holidays.

In Anne Arundel County, home to Fort Meade and the National Security Agency, state roads are clogging because of the NSA’s recent, gradual expansion and the addition of three new Defense Department groups. And back in 2005, the National Institutes of Health left its Bethesda neighbors stewing over a new security fence that cut off jogging paths and a convenient walk to the Metro station.

The situation in Bethesda grows out of the relocation of the National Geospatial Intelligence Agency. From the 1940s until this year, residents off MacArthur Boulevard lived near the government mapping agency, whose analysts interpret spy satellite imagery and build high-tech digital maps. But this year, the agency moved to Fort Belvoir in Northern Virginia as part of the federal Base Realignment and Closure plan.

Now, the government wants to transform the mapping agency’s campus, about 40 acres of mostly windowless red brick buildings, into a gleaming complex to house as many as 3,000 employees of various intelligence agencies.

In public hearings, the government has kept mum about which agencies will occupy the campus. But in an interview this month, a spokeswoman for the Defense Intelligence Agency, Laura Donnelly, said employees of at least two agencies — the DIA and the Office of the Director of National Intelligence — will be housed at the site. She also said the National Intelligence University, exclusively for armed services members and civilian federal employees with security clearances, is moving there.

Employees of other, as-yet-to-be-determined intelligence branches could be coming to the campus, too. Donnelly declined to identify the campus’s overall mission, other than to say it will bolster national security.

The public at least has a general sense of what goes on behind the gates of other secret agencies. At Langley, the CIA directs covert paramilitary operations and analyzes intelligence gathered by its global network of spies. At Fort Meade, the NSA monitors and analyzes foreign electronic communications and safeguards U.S. government communications and data systems.

In Bethesda, residents in the MacArthur Boulevard area feel somewhat clueless about what will go on at the mysterious Intelligence Community Campus.

“Do you think they told Montgomery Council President Berliner who is going to be there?” asked Montgomery County Council President Roger Berliner (D-Potomac-Bethesda). “I’m just gratified they don’t need a heliport. That would have been a nightmare for the community.”

Neighbors are especially irritated by the planned six-level parking structure — three stories high, with parking on the roof and two stories visible below grade — that they say will bring an onslaught of headlights through their windows and spoil scenic views along the Potomac.

An intelligence complex, most neighbors agree, is better than a big-box store. Still, residents hope to have the garage, or most of it, built underground or below grade and without encroaching on the surrounding woodland or cutting down trees.

“The intelligence community is a big enemy to fight because they have unlimited legal defense, and most of the planning for this has been done in secret,” said Roger Herst, a commercial real estate developer, rabbi and novelist whose home faces the campus’s wooded backside and the location of the planned garage.

Public notices about the intelligence campus were sent to local and state agencies in late 2010. Neighbors said that they asked at the time to meet with the Army Corps, which is designing the project with the DIA, but that nothing was scheduled then. It wasn’t until October and December that neighbors met with the Army Corps — shortly after a nearly $40 million design-and-construction contract for the campus was awarded. Construction is expected to begin in early 2012.

Donnelly, the DIA spokeswoman, said the campus’s design first had to be approved by other intelligence agencies and members of Congress before any public meetings could be held with members of the community. After they heard from neighbors at the public meeting in October, DIA officials said the garage was redesigned to take up less wooded area.

But the neighborhood’s demands for an underground garage — and ideally no tree cutting — would require the government to spend more money than budgeted.

Jesse L. Goodman and his wife, Nicole Lurie, are among the neighbors most aggressively campaigning against the garage’s design. He’s the FDA’s chief scientist and deputy commissioner for science and public health; she’s the assistant secretary for preparedness and response at HHS. Their bedroom windows would look right into the garage.

“This hadn’t been seen by us as something imminent,” Goodman said. “The Army Corps’ project was done in a manner that was not transparent. I am not even sure that their ‘customer’ — so to speak — recognized the level of neighborhood impact.”

Kevin Brandt, the superintendent of Chesapeake & Ohio Canal National Historical Park, said he was not so alarmed initially by the project because the Army Corps told his staff in January that no trees would be cut down. Now he knows that trees will be removed, but he says the Army Corps hasn’t provided an approximate number. (The Army Corps told The Washington Post that as much as two acres will be cleared.)

“We just don’t know enough information about the plans. Certainly in other national parks, you haven’t had this super-secret kind of stuff going on,” Brandt said. “The things we’re concerned about we’d be asking any new neighbor, like a Wal-Mart.”

Now the DIA and the Army Corps are seeking approval from the National Capital Planning Commission. The commission, a federal agency, delayed a decision early this month, requiring the Army Corps to return with alternative garage designs. The panel is expected to review the campus’s plans in February, but its decision won’t be binding.

In an interview, Olsen, the Army Corps official, declined to say whether the agency will proceed if the federal commission rejects the plan. He said the new garage would be no taller than structures now on the site. “Our principal focus is to be a good neighbor,” Olsen said.

Meanwhile, the Bethesda neighbors worry that the Intelligence Community Campus will be more disruptive than the old, low-key mapping agency. Herst, the developer-rabbi-novelist, speculated that more security vehicles will roam up and down his secluded street for some mysterious purpose.

“Who knows who these secret organizations really report to?” he said. “They do what they want.”