Since news broke last month that Google is working on a censored search engine for the Chinese market, the company has faced unrelenting criticism from lawmakers. In the latest demand, a bipartisan group of 16 House representatives is looking for answers on the still-secretive plan.

The project has ignited controversy

To launch the project, reportedly called Dragonfly, Google would have to cooperate with the Chinese government’s strict surveillance and censorship measures, a prospect that has ignited controversy inside and outside the company. Last month, a bipartisan group of senators sent a letter to CEO Sundar Pichai about the project, but his response was blasted as insufficient.

Criticism of the company has only accelerated since. Google declined to make top executives available for a Senate Intelligence Committee hearing on social media earlier this month, leading to an empty chair during the hearing. (“We’d understood that our SVP of Global Affairs would be an appropriate witness for the social media hearing so we formally announced his attendance in mid-August,” a Google spokesperson said.) President Trump has also recently charged the company with dubious claims of bias against conservatives.

Yesterday’s letter, also addressed to Pichai, questions Google’s decision to return to China after leaving in 2010. Since that time, the lawmakers write, the government’s monitoring practices have only grown, even after being “quite robust.”

“As policymakers, we have a responsibility to ensure that American companies are not perpetuating human rights abuses abroad, and to ensure that our regulatory and statutory systems are able to deal with changing business environments,” the letter reads.

The lawmakers are requesting more details on the company’s plans. Among the questions for the company: what restrictions will it place on the search engine? And if Google left China in 2010, why has it decided to move back now?

Google declined to comment on the letter. “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,” the company said in a previous statement. “But our work on search has been exploratory, and we are not close to launching a search product in China.”