Battle lines were being drawn Wednesday over a US federal judge's order that Apple help the FBI crack the encryption on an iPhone linked to the San Bernardino, California, terror attack.
Apple chief executive Tim Cook refused the judge's order in an open letter posted on the company's website Tuesday shortly after Judge Sheri Pym ordered the company to help the FBI access data they believe is stored on the phone.
The December 2 attack in San Bernardino was carried out by Syed Rizwan Farook and his wife, Tashfeen Malik, at a holiday party at the county office where Farook worked. Fourteen people were killed.
Police killed Farook and Malik later that same day in a shoot-out.
The FBI wants Apple to help it hack into Farook's iPhone by building a new version of the iOS software that would circumvent security features and install the software on the iPhone, which was recovered during the investigation.
The White House Wednesday called the case an "important national priority." Spokesman Josh Earnest downplayed the request, saying investigators were simply asking for a way in to this single device.
But Cook said there was no way to guarantee those limits, and that cracking this device "would undeniably create a backdoor" to all iPhones and other encrypted Apple devices.
"The US 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," Cook said. Such a move would "undermine the very freedoms and liberty our government is meant to protect."
The implications of the government's demands are "chilling," he said because it would give the government the power to reach into anyone's device to capture their data.
The American Civil Liberties Union, the nation's leading legal rights group, praised Cook and said it would support Apple in the legal battle to come.
In a press release, the ACLU pointed out "if the FBI can force Apple to hack into iPhones, then so too can every repressive regime in the world."
Fugitive cyberspying whistle-blower Edward Snowden agreed. In a message on Twitter he wrote, "the FBI is creating a world where citizens rely on Apple to defend their rights, rather than the other way around."
Snowden said the software the FBI is demanding would enable iPhone encryption to be cracked in half an hour.
The issue of encryption has been a source of tension between technology companies and law enforcement for decades.
Tech producers build in encryption to protect customers' privacy. In some cases the companies themselves cannot even crack the encryption.
But the ability to communicate without fear of government surveillance potentially creates cover for criminals and terrorists too.
Cook's letter said Apple already had done everything in its power and within the law to help the FBI.
"Opposing this order is not something we take lightly," Cook wrote. "We feel we must speak up in the face of what we see as an overreach by the US government."