Diners enjoy the patio seating at a Capitol Hill bar in the summer of 2011. (Amanda Voisard/The Washington Post)

The briefing was held in a private banquet room about 1,000 feet from the White House. The FBI was there. The Department of Homeland Security was there. So were staffers from the 9:30 Club and the Black Cat, gay bars Number Nine and Trade, and dozens of other nightlife spots and restaurants.

The message was both dire and obvious, once unthinkable and now unavoidable: You know those terrorists who want to attack Washington?

Forget the Capitol. Next time, they might come for your happy hour.

To hammer it home, law enforcement officials shared images of Islamic State and al-Qaeda propaganda that encourage attacks on American social spots.

“These guys were terrifying,” says Bill Duggan, proprietor of Madam’s Organ. “They said, ‘For your business, you have to have a plan of succession.’  ”

As in, who will be in charge if your front-door guy is bleeding out on the sidewalk.

Washington is a city of hard targets. Monuments. The executive mansion. Agency headquarters. All ringed by concrete planters, steel bollards and armed guards.

It is also a city of soft targets. Crowded clubs. Sunny beer gardens. Outdoor movie screenings. Insulated only by a door, a railing, a 45-minute wait for a table, maybe a cursory bag check.

Is it only a matter of time? With every terrorist attack of the past 15 years, a different aspect of modern life has suddenly seemed vulnerable: Jets. Skyscrapers. Even the mail. That’s what terrorism does: It chips away at our confidence in the security of routine.

Despite the seriousness of their recent briefing, officials emphasized that there are no specific, credible threats against D.C. nightlife.

Terrorists, though, have gone after soft targets for years. Radical Islamist groups bombed a nightlife strip in Bali in 2002, shot up a shopping mall in Kenya in 2013, killed and injured scores last month in a park in Pakistan; the 2013 Boston Marathon was shattered by the fatal explosions set by a pair of self-radicalized brothers.

But the tactic reentered Western territory in a big way in November, when Islamic State militants massacred patrons of a concert hall and cafe in Paris and set off explosions at a soccer stadium.

Investigators search for evidence outside the Comptoir Voltaire cafe after the terrorist attacks in Paris in November. (Kenzo Tribouillard/Agence France-Presse via Getty Images)

This wasn’t an attack on transit, like the ones in Madrid in 2004 and London in 2005, with the aim of paralyzing the nervous system of a metropolitan area. This was hitting people in the act of pleasure, not business — people who weren’t going to, or coming from. People who were at their destination, just enjoying life.

“By God, as we struck France at the center of its abode in Paris, then we swear we will strike America at its center in Washington,” said a man identified as “Al Karar the Iraqi” in an alleged Islamic State propaganda video released shortly afterward.

Does that mean the White House?

Or your favorite brunch spot?

“Don’t care, blow me up,” says Mathew Ashley, 41, after finishing a salmon burger on the patio of Brasserie Beck, the Belgian restaurant on K Street NW, on one of the spring’s first temperate evenings. The recent attacks on the Brussels airport and metro system are not on his mind.

“The best thing we can do is just keep on living,” says his dining companion Kirsten Feyling, 36, who works as a fundraiser. “It’s going to be fine.”

The Paris attacks prompted the Jan. 19 briefing at Joe’s Seafood, Prime Steak & Stone Crab in downtown Washington, organized by the District’s nightlife and restaurant associations as well as its downtown business improvement district. Officials at the meeting emphasized that there was no specific threat but that venues should have rally points for staffers and floor plans available for law enforcement.

The FBI and Homeland Security routinely coordinate these mass briefings for other private organizations, including media companies, religious organizations and tourism offices. The D.C. police hosted a general briefing for the city’s nightlife operators in April 2014. The Jan. 19 briefing wasn’t all that frightening, says one longtime D.C. nightclub owner — but it left some attendees wanting more than just hotlines, pamphlets and run-hide-fight videos.

“I don’t understand how emergency preparedness actually works in this town,” says the owner, who spoke on the condition of anonymity because he didn’t want to associate his venue with terrorism paranoia. “Suppose there’s a dirty bomb downtown. What’s the process for figuring out what’s going on? Should [patrons] shelter in place? Should they leave? How would I deal with a large crowd having to go or having to stay? . . . I have a feeling if something bad happened in this city, I would be stuck watching the news” for any information.

Bad things happen routinely in this city, as in any city. There have been lockdowns and suspicious packages and the 2013 workplace shooting at the Navy Yard. Metro is running an announcement in subway stations that references the Brussels attacks and says “all of us have a role to play in keeping the system safe.”

But nothing’s exploded yet. There’s been no armed assault on a local watering hole.

People have tried and failed. A Moroccan man living in Fairfax was arrested in 2012 and charged with attempting to use a weapon of mass destruction against federal property. At one point he considered bombing Bistro Bis on Capitol Hill or the restaurant Aria on Pennsylvania Avenue NW, according to Washingtonian magazine.

Everything is going to be fine. Right?

Vincent Kunze is having a smoke outside the Black Cat about 10:30 p.m. on a Thursday. Friends of his, on their way to the airport the previous day, were preoccupied by Brussels, he says.

But is terrorism on his mind at the concert this night?

“It’s no real concern at all, which is kind of troubling,” says Kunze, 29, a graduate student from northern Germany. “This is the second or third attack in Europe in a year. It’s disturbing that it’s become normal.”

People line up outside the Black Cat on 14th Street in Northwest Washington in 2014. (Evelyn Hockstein/For The Washington Post)

Crowds gather to watch a movie on the Mall in the summer of 2003. (Tyler Mallory/For The Washington Post)

And hence the Jan. 19 briefing, which morphed into a debate about a more mundane security concern: the proliferation of fake IDs. Good forgeries from China are making their way into the purses and wallets of underage Washingtonians. Some in the local hospitality industry see a lack of cooperation and aggression from law enforcement on the fake-ID front.

Security “is broken at a fundamental level,” says Park at Fourteenth owner Marc Barnes, who dismisses the Jan. 19 briefing as “superficial.” Local authorities “aren’t handling the bottom part of it: Why don’t we get the IDs under control? Why can’t the whole country have the same ID?”

If you can’t vanquish 19-year-old Becky from Ballston, in other words, how are you supposed to stop a lone-wolf gunman or a suicide bomber?

Operators are “being told, ‘See something, say something. Be on top of your game. Know who’s coming in.’ But the reality is: How can we do that?” says Mark Lee, executive director of the D.C. Nightlife Hospitality Association.

IDs may be a problem at some venues, says Lt. Sean Conboy, a public information officer for the D.C. police. But officers are already working overtime shifts that assign them to individual nightlife spots, partnering with the bars or clubs to manage security. Plus, the department fields dedicated nightlife units across the city and “regularly conducts underage enforcement through the city” in cooperation with front-door staffs, Conboy said.

Federal Washington might be well-defended — last month a gunman at the U.S. Capitol Visitor Center was thwarted by security guards — but regular Washington is like any other city: a clean, easy target, according to former detective Robert C. Smith, the chief executive of Nightclub Security Consultants.

Smith, who trains hospitality staffs across the country, says that he started worrying 10 years ago about a Paris-style attack, and that vigilance and diligence at a basic level are more crucial than ever.

“A bouncer, a hotel clerk, a door host are on the front lines of fighting terrorism,” Smith says, “more than Customs [and] Border Protection or Border Patrol.”

So Washington goes about its business, and the business of pleasure, barricaded to the hilt but still vulnerable. Last week, the Mount Vernon and Shaw neighborhoods turned into a gated kingdom for the Nuclear Security Summit. Metro is as crowded and seemingly vulnerable as ever. Spring means open outdoor seating is at a premium.

And the people in charge are worrying so we don’t have to. If patrons at Madam’s Organ ask why their bags are being checked, for example, the doormen have been instructed to say they’re checking for outside liquor. No need to alarm anyone.

“But truthfully,” says Duggan, the owner, “we’re looking for bombs.”