Google employees have renewed their public protests against “Project Dragonfly,” a censored and surveillance-enabling search app that Google is reportedly building for the Chinese market. An open letter, published on Medium today, says Dragonfly would make Google complicit in human rights abuses by the Chinese government. It urges Google leadership to cancel the project and accuses them of ignoring repeated employee complaints.

Over a thousand Google employees signed a letter protesting Dragonfly in August. This new Medium post focuses on similar concerns, but it’s being posted online, rather than circulated internally. “Google leadership has failed to respond to employees who have raised questions for months,” it says. “So far, there have been no satisfactory answers.”

The letter outlines the core problems with Dragonfly: it would help the Chinese government extend its already extensive surveillance state, and it would signal that Google is willing to capitulate to other governments who want to censor the internet.

Our company’s decision comes at a time when the Chinese government is openly expanding its surveillance powers and mechanisms for population control. Many of these rely on advanced technologies, and combine online activity, personal records, and mass monitoring to track and profile citizens. Reports are already showing who bears the cost, including Uyghurs, women’s rights advocates, and students. Giving the Chinese government ready access to user data, as required by Chinese law, would make Google complicit in oppression and human rights abuses. Dragonfly would also enable censorship and government-directed disinformation, and destabilize the ground truth on which popular deliberation and dissent rely. Given the Chinese government’s reported suppression of dissident voices, such controls would likely be used to silence marginalized people, and favor information that promotes government interests. We refuse to build technologies that aid the powerful in oppressing the vulnerable, wherever they may be. The Chinese government certainly isn’t alone in its readiness to stifle freedom of expression, and to use surveillance to repress dissent. Dragonfly in China would establish a dangerous precedent, one that would make it harder for Google to deny other countries similar concessions.

Google has said little about Dragonfly, but numerous reports have detailed its planned features, which reportedly range from blocking specific keywords like “human rights” to linking searches with users’ phone numbers. Its existence caused one former senior research scientist, Jack Poulson, to resign in protest. The new letter is currently signed by 11 employees, including Google Open Research lead Meredith Whittaker.

This letter comes as Amnesty International protestors gather outside Google offices to protest Dragonfly. In a press release, technology and human rights researcher Joe Westby called the app “a watershed moment for Google.” Releasing Dragonfly would reverse a decision made in 2010 when Google pulled out of China to avoid working with government censors.

Many of us accepted employment at Google with the company’s values in mind, including its previous position on Chinese censorship and surveillance, and an understanding that Google was a company willing to place its values above its profits. After a year of disappointments including Project Maven, Dragonfly, and Google’s support for abusers, we no longer believe this is the case. This is why we’re taking a stand. We join with Amnesty International in demanding that Dragonfly be canceled. We also demand that leadership commit to transparency, clear communication, and real accountability. We deserve to know what we’re building and we deserve a say in these significant decisions.

Employees at other companies have previously used Medium as a way to highlight problems: Amazon and Microsoft employees published letters raising concerns about military contracts last month. And as the letter indicates, Google has raised employees’ ire multiple times this year. It signed a deal with the US government for a military AI system called Project Maven, which it wound down after protests. Thousands of Google employees also protested the company’s handling of sexual assault and harassment allegations, leading Google to change how it handled sexual misconduct.

When reached for comment, a Google spokesperson directed The Verge to an earlier comment. “We’ve been investing for many years to help Chinese users, from developing Android, through mobile apps such as Google Translate and Files Go, and our developer tools. But our work on search has been exploratory, and we are not close to launching a search product in China,” it reads.

Update 10:00AM ET: Added comment from Google.