In an interview with BuzzFeed News, Apple CEO Tim Cook called on Bloomberg to retract its story alleging that Chinese spies compromised a company server through the use of malicious microchips. It’s the first time Cook has gone on the record to contest the allegations.

“This did not happen. There’s no truth to this,” Cook said in the interview.

The initial Bloomberg report alleged that Chinese spies were able to infiltrate critical tech infrastructure belonging to companies like Apple and Amazon by injecting tiny microchips inside Supermicro servers. Allegedly, these hardware manipulations allowed the Chinese government backdoor access into computer networks run on those servers.

Quickly after the report’s publication, Apple released a statement picking the story apart, denying each individual claim. “On this we can be very clear: Apple has never found malicious chips, ‘hardware manipulations’ or vulnerabilities purposely planted in any server,” the release said. Soon after, the company’s vice president of information security, George Stathakopoulos, wrote to Congress denying the allegations directly.

In the interview with BuzzFeed, Cook said that he “was involved in our response to this story from the beginning.” In the company’s correspondence with Bloomberg, Cook said that “[Apple was] very clear with them that this did not happen, and answered all their questions.”

The report has continued to garner criticism from US intel chiefs and cybersecurity experts. No malicious chips have surfaced, and no evidence has been proposed in the weeks following the release of the report. One of the named sources said in a podcast that the claims “didn’t make any sense.”

“Each time they brought this up to us, the story changed and each time we investigated we found nothing,” Cook said.