BEIJING — Shortly after 7:30 p.m., the servers at China's biggest North Korean restaurant become singers. They emerge for their nightly performances in orange and purple satin dresses and stiletto heels, belting out ballads with their arms extended, would-be divas shimmering under hot lights.

On some other night, when the house is packed and the soju flowing, this might set off a drunken singalong, with tables of South Korean tourists clapping wholesomely in the front and smoky huddles of their expat businessmen compatriots leering not-so-wholesomely from the back.

But not tonight.

In the northeast corner of Beijing, the Okryugwan restaurant is feeling the far-flung effects of the latest standoff on the Korean Peninsula. Since the North conducted a nuclear test in January and went ahead with a rocket launch earlier this month, Seoul has instructed its citizens to not patronize the government-affiliated North Korean restaurants that usually pull in a steady stream of curious South Korean travelers and their precious foreign currency.

“We usually have many tables of South Korean tourists, but business is not good,” North Korean server Han Ahn Min said as she poured tea at one of just a handful of occupied tables in a high-ceilinged dining hall capable of welcoming visitors by the busload.

“The weather is bad,” she said in smooth Mandarin and smiled. “There are the other factors right now, too.”

That was as close as Han, a talkative 24-year-old with a ready routine of questions and answers, would get to discussing the South or politics.

The Okryugwan is an offshoot of a well-known eatery in central Pyongyang.

South Korean intelligence estimates North Korea runs about 130 overseas restaurants that generate more than $100 million annually, a figure that would approach what 45,000 North Korean laborers made last year at the jointly-run Kaesong industrial park near the border between the two neighbors.

The South believes the North's overseas businesses bring in critical foreign currency for its weapons program, among other things, and recently shut down the Kaesong complex while calling for more stringent economic sanctions.

Seoul's campaign to starve the North's restaurant business appears to be well communicated, if not always well heeded.

A wholly unscientific survey of the Okryugwan clientele one recent night showed that two of the five occupied tables were seated with South Koreans, all of whom knew about the government warning. Elderly Chinese lined another table, while yet another was seated with several North Koreans, wait staff said, including, briefly at one point, one of the cooks.

Despite the small, tepid crowd, the performers powered through several songs and wardrobe changes, swapping form-fitting satin dresses for flowing traditional robes. They launched into Korean and Chinese songs and showed off — or at least mimicked — dazzling technique on accordions, guitars and saxophones, all against a looming, painted backdrop of turquoise waves crashing against cliffs.

Over thin applause, the soprano who gamely closed out the night's show received a bouquet of flowers from what appeared to be another employee who shuffled over from the back.

A cursory peek into a cozier, second-floor bar and restaurant popular with hard-drinking South Korean businessmen suggested other North Korean locations in town weren't better off. Branches in Bangkok and Phnom Penh were relatively deserted, too.

The Bangkok show was a half-hour of skilled performances and lightning-fast costume changes, from traditional hanboks to sparkly short dresses in the style of K-pop girl bands. A slide show in the background depicted flowers, landscapes, tundra and a river full of dead fish.

The server/performers played instruments including a guitar, saxophone and a 12-stringed, gayageum with cool precision. When off stage, as they engaged elderly patrons in conversation, their smiles vanished as soon as they turned around.

Known for highly attentive service and decent food, the restaurants have long been a popular stop for South Korean travelers seeking a glimpse into their isolated neighbor and a modicum of open dialogue with well-trained servers who give straightforward answers to many questions while skillfully eluding sensitive ones.

The establishments serve as listening posts and cultural outposts, experts say. Well-educated employees like Han, who studied business and must return to North Korea after a three-to-four-year stint, gauge local sentiment as they aggressively push domestic beer ($6 a bottle), cigarettes ($5 a pack), and collectible stamp books ($100 each).

The menu, while not terribly expansive, wasn't cheap either, featuring $20 sushi platters, $10 dog meat stews and pricey grilled steak cuts calculated by weight.

“What do Chinese think of North Korea?” asked Han, the North Korea server, once the lights went up.

After the audience responded she exclaimed, “Korean-Chinese friendship!” and touted the stamp collection, with illustrations of North Korean founder Kim Il Sung and China's Mao Zedong, old Communist allies.

Lee Seunghyun, a 25-year-old who works in the furniture business in Beijing, was sitting at a rear table with a friend on a weeklong visit from Seoul. Despite government warnings, the friend made a point of checking out the restaurant because Lee's grandparents had left North Korea before the split.

“We saw the warnings, but he was very curious,” Lee said as her friend pulled out his smartphone to show a series of cautionary text messages sent by the South Korean foreign ministry to citizens traveling in China.

Although they found the experience “interesting,” the South Koreans said they were ready to leave after their servers, who initially spoke relatively openly about the slow business and agreed to take selfies together, turned cold after the pair declined to buy cases of beer or cartons of cigarettes.

After that, there was only one table of South Koreans left.

Puffing on a cigarette outside the restaurant, a local assistant to a South Korean broadcaster confided that the table was a crew filming a program in China, all well aware that they shouldn't be patronizing the establishment. He grimaced once he learned he was speaking to a reporter but kept talking. Finally, he pleaded: Forget this conversation.

“Come on, do a favor for a fellow journalist,” he said as he walked back into an emptying restaurant. “We're really not supposed to be here.”