The U.S. Department of Defense's outgoing chief data officer called for the Pentagon to make urgent investments to defend against potential espionage from quantum computers -- nascent technology that could one day break the encryption that protects American secrets.

In his first interview since leaving his post last month, David Spirk, who spent two years in his role, told Bloomberg News that the Pentagon needs to speed up efforts to counter adversaries who are developing military tools supported by advanced technologies such as artificial intelligence, machine learning and eventually quantum science.

Quantum computing may prove far more able than existing technology to solve mathematical problems at exponentially faster speeds. That could enable operators to unscramble the algorithms that underpin encryption protocols, unlocking an array of sensitive data.

"I don't think that there's enough senior leaders getting their heads around the implications of quantum," Spirk said. "Like AI, I think that's a new wave of compute that when it arrives is going to be a pretty shocking moment to industry and government alike."

"We have to pick up pace because we have competitors who are also attempting to accelerate," he added.

Spirk's comments come amid warnings that U.S. adversaries, particularly China, are aggressively pursuing advanced technologies that could radically accelerate the pace of modern warfare. China is investing in AI and quantum sciences as part of its plan to become an innovation superpower, according to the Pentagon's latest annual report to Congress on China's military power. China is "at or near the lead on numerous science fields," including AI and quantum, it said.

The National Security Agency, meanwhile, said last year that the adversarial use of a quantum computer "could be devastating" to the U.S. and its national security systems. The NSA said it could take 20 years or more to roll out new post-quantum cryptography that would resist such code-cracking.

Tim Gorman, a spokesperson at the Pentagon, said the Department of Defense was taking post-quantum cryptography seriously and coordinating with Congress and across government agencies. He added there was "a significant effort" underway.

A January presidential memo further charged agencies with establishing a timeline for transitioning to quantum resistant cryptography.

Among the efforts underway to bolster defenses against quantum-based attacks, the National Institute of Standards and Technology, known as NIST, is seeking to select new quantum-proof encryption algorithms from seven finalists shortly as part of a global competition.

Jonathan Katz, computer science professor at the University of Maryland who submitted a "post-quantum algorithm" to the NIST competition, said the stakes in the NIST competition were high: an algorithm that later proved vulnerable would be "a disaster." Once a choice is made, the U.S. Department of Defense faces a huge task in upgrading all its software and hardware that features algorithms, he said, adding that included not only servers and laptops but also parts of submarines, tanks, helicopters and weapons systems.

Experts generally assess large-scale quantum computing may be 15 to 20 years away if it is ever even developed, but the Pentagon's Defense Advanced Research Agency, or DARPA, launched a project this February to explore the possibility that a breakthrough could be developed "much sooner."

Joe Altepeter, who manages DARPA's new quantum project, told Bloomberg there was a lot of "hype" over industry claims about the arrival of quantum computing, with several "hardware miracles" still standing in the way. Some of the smartest physicists he knew were divided over whether useful quantum computing would ever exist, Altepeter said, adding that the risk was such that it was important to develop resilient systems.

Spirk said the Pentagon needs to start preparing "now," arguing military applications for quantum computing could be only five to 10 years away. The Pentagon needed to work at the same speed as commercial vendors that are already exploring ways to use quantum-resistant cryptography to safeguard financial and health-care sectors, he said.

If the U.S. doesn't make the right investments in defensive quantum today, "then our concepts around encryption, data security and cybersecurity will be obsolete because the computers will break our cryptography," Spirk said. He added that all the encrypted data that adversaries have already gathered would also risk exposure.

Spirk, a former U.S. Marine, became the first chief data officer at Special Operations Command before he joined the Pentagon. He said he left the chief data officer post after a two-year commitment to rejoin his family in Florida. The departure follows last year's resignation of the U.S. Air Force's first chief software officer, Nicolas Chaillan, who previously told the Financial Times that the U.S. was losing the AI race to China.