The path to restoring any semblance of digital privacy in the United States is going to require more scrutiny over the practices of companies that collect and sell user data, according to Apple CEO Tim Cook.

At a time when Cook’s Silicon Valley neighbors, including Google and Facebook, are under scrutiny for their data collection and privacy practices, Cook has been vocal about the need for a comprehensive privacy law in the United States.

In an essay published in Time magazine on Thursday, Cook honed in on data brokers, companies that collect massive amounts of data on people and then sell it. He called on the Federal Trade Commission to create a data broker clearinghouse, which would require them to report transparency information, while giving consumers the ability to learn what companies know about them and delete that information.

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“Meaningful, comprehensive federal privacy legislation should not only aim to put consumers in control of their data, it should also shine a light on actors trafficking in your data behind the scenes,” Cook wrote.

A new Vermont law requires data brokers to register with the state by the end of January and provide transparency information, such as if and how consumers can opt out of having their data sold, security breaches or whether they knowingly hold information about minors. However, Cook said a law is needed at the national level to protect all Americans.

Data brokers collect and store billions of data points that can be traced back to almost every person in the U.S., according to an FTC report released in 2014. The report said the data broker industry is “complex” and with many brokers providing data to each other, it’s impossible to get to the root of where a piece of information may have first been collected.

“Consumers shouldn’t have to tolerate another year of companies irresponsibly amassing huge user profiles, data breaches that seem out of control and the vanishing ability to control our own digital lives,” Cook wrote. “This problem is solvable—it isn’t too big, too challenging or too late.”

Cook has long positioned Apple as a protector of user privacy but has become even more vocal about it amid the backlash against technology companies. In October, Cook told regulators gathered in Brussels for the International Conference of Data Protection and Privacy Commissioners that he supports a privacy law in the United States modeled along the lines of Europe’s GDPR, which puts data ownership in the hands of consumers and imposes stiff fines on companies that don’t properly protect user data.

Cook also went after Mark Zuckerberg in March and said that Facebook should have self-regulated, but added, “I think we’re beyond that here.” Cook has also sought to position Apple as the face of “responsible tech,” adding more privacy controls for users, including secure password management, and bolstering its intelligent tracking feature in Safari, preventing companies from tracking users as they browse the internet.

In 2016, he also declined to cooperate with an FBI request to unlock the encrypted iPhone of one of the San Bernardino shooters, arguing that even if they could, it would create a slippery slope and have privacy implications for future cases.