"Hoped to serve your people? Ended up spying on them? Exit intelligence."

These were the messages on billboards that appeared on Monday outside of the headquarters of the National Security Agency (NSA) at Fort Meade, Md. According to photographer Ben Grad, who accompanied a van bearing the billboard and took the pictures of it, organizers of the campaign stayed in the area near Fort Meade for nearly the whole day. Around noon, they spent around two hours near Cafe Joe, considered to be a popular lunch venue among the NSA workers, until an office manager who took them for "recruiters" asked them not to stay too long, Grad told the WorldViews.

Among those who joined the campaign in Fort Meade was Thomas Drake, a former NSA executive and whistleblower.

Similar billboards appeared on the same day in Berlin, in front of the headquarters of the German secret service BND, and in Cheltenham, U.K., outside of the headquarters of the British intelligence agency GCHQ. In Germany and Britain, campaigners also tried to distribute some flyers:

The billboards promoted a project called Intelexit that claims to help secret service agents quit their jobs. Its Web site welcomes its visitors with an advertisement video that ends with a slogan: "Be smart. Exit intelligence now."

The page also allows users to generate a "resignation letter" by clicking through the possible reasons for an exit that vary between options like "Working in intelligence makes me feel lonely because I can't talk to anybody about my success or about my doubts and critiques" and "The intelligence agency I work for lost its ethical compass."

The FAQ section answers the questions that potential dropouts or whistleblowers could have, in the opinion of the authors of the project: Will I lose my friends? (the answer is: "Real friends should stick with you if you leave your job") or What do I need to make a decision? (the advice is to think about it between two months and two years). Intelexit suggests those who decided to exit contact them via encrypted e-mail or leave an anonymous message via a Tor hidden service, and promises help or legal support if needed.

The project was started by the Berlin-based group of artists and activists Peng! Collective. The group is known for its performances, parodies and sophisticated campaigns.

Two months ago, the group launched a Web site encouraging European tourists to smuggle refugees when they drive home from their vacations — several people actually did it. Last year, activists appeared at the tech conference Re:publica in Berlin and presented new "Google products" including personal drones.

Jérémie Zimmermann, a French net activist who works with the group on the Intelexit campaign, says they have a serious goal of drawing public attention to the moral aspects of working for intelligence agencies. "We hope that more intelligence workers can discuss it openly, even if while talking to each other at the coffee machine in their office," he told WorldViews.

The activists were inspired by their encounters with some employees of secret services who "hinted at their moral despair," Zimmermann said. Several people have contacted the project since its launch, though he added that it wasn't possible to verify if they were real intelligence officers.

The interest in front of the NSA headquarters was not overwhelming. "There was not a lot of reaction," the photographer Grad told WorldViews. The people who asked the most questions appeared to be the officers who stopped him near the NSA campus and told to delete pictures with the NSA building in the background. They were "good humored," he said.

But it didn't look like they were persuaded to quit.