Hours after a federal judge ordered Apple to help the FBI break into the iPhone of one of the San Bernardino shooters, Apple CEO Tim Cook shot back with a fiercely worded letter promising to fight the order.

“They have asked us to build a backdoor to the iPhone,” Cook wrote. “While we believe the FBI’s intentions are good, it would be wrong for the government to force us to build a backdoor into our products. And ultimately, we fear that this demand would undermine the very freedoms and liberty our government is meant to protect.”

Two months after the deadly California shootings, the iPhone‘s default encryption has kept the Federal Bureau of Investigation from fully accessing the phone’s data. The court order directed Apple to provide “reasonable technical assistance” to recover critical data from the iPhone 5c, including bypassing the phone’s auto-erase function and allowing investigators to submit an unlimited number of passwords in their attempts to unlock the phone.

“The United States government has demanded that Apple take an unprecedented step which threatens the security of our customers,” Cook said. “We oppose this order, which has implications far beyond the legal case at hand.”

[T]he U.S. government has asked us for something we simply do not have, and something we consider too dangerous to create. They have asked us to build a backdoor to the iPhone. Specifically, the FBI wants us to make a new version of the iPhone operating system, circumventing several important security features, and install it on an iPhone recovered during the investigation. In the wrong hands, this software — which does not exist today — would have the potential to unlock any iPhone in someone’s physical possession. They have asked us to build a backdoor to the iPhone.

Cook wrote that Apple had “great respect for the professionals at the FBI” and had provided help in the form of data when Apple possesses it, engineers when they could advise the FBI, and ideas for how best to proceed with investigations.

Cook continued:

The government suggests this tool could only be used once, on one phone. But that’s simply not true. Once created, the technique could be used over and over again, on any number of devices. In the physical world, it would be the equivalent of a master key, capable of opening hundreds of millions of locks — from restaurants and banks to stores and homes. No reasonable person would find that acceptable. The government is asking Apple to hack our own users and undermine decades of security advancements that protect our customers — including tens of millions of American citizens — from sophisticated hackers and cybercriminals.

Cook has become the most prominent voice fighting government attempts to guarantee law-enforcement access to encrypted products, publicly warning against undermining end-to-end encryption. At a recent White House summit, he reportedly argued forcefully with FBI Director James Comey and Attorney General Loretta Lynch over their support for encryption backdoors.

A statement in Apple’s s privacy policy written by Cook claims that the company has “never worked with any government agency from any country to create a backdoor in any of our products or services. We have also never allowed access to our servers. And we never will.”

“We are challenging the FBI’s demands with the deepest respect for American democracy and a love of our country,” Cook wrote in Wednesday morning’s letter. “Ultimately, we fear that this demand would undermine the very freedoms and liberty our government is meant to protect.”

Photo via thierry ehrmann/Flickr (CC BY 2.0)