Program managers had worked to resolve problems discovered in previous years, and security was improving, but this year's testing had revealed new vulnerabilities, the Pentagon’s chief weapons tester, Michael Gilmore, said in his annual report that was released Tuesday.
Those vulnerabilities include misconfigured, unpatched and outdated software, Reuters reported.
"Cyber adversaries have become as serious a threat to U.S. military forces as the air, land, sea and undersea threats represented in operational testing for decades," Gilmore wrote in the 366-page report.
"The continued development of advanced cyber intrusion techniques makes it likely that determined cyber adversaries can acquire a foothold in most (Department of Defense) networks, and could be in a position to degrade important DOD missions when and if they chose to," he continued.
The troubling report was released days after NSA whistleblower Edward Snowden leaked documents accusing China of stealing "many terabytes" of data about the Lockheed Martin Corp F-35 fighter jet, the crown jewel of American military aircraft.
The Pentagon had previously admitted hackers were able to breach governmental networks, but never pointed to China and claimed that no classified information was taken.
China’s version of the stealth fighter, the newly released J-31, has design elements similar to that of the F-35, defense experts told Reuters, but Chinese authorities denied the hack claim.
The report cited numerous violations of Pentagon password policies, and many problems that could have been addressed when programs were still in development. Even novice techniques had allowed testers to penetrate networks, the report said.
Gilmore said it was critical to follow up cyber testing of weapons with an "adversarial assessment," in which officials pose as enemies and try to hack into systems. He noted the U.S. military also had a critical shortfall of cyber personnel.
Tests of more than 40 weapons revealed problems with cybersecurity, and Gilmore said U.S. soldiers needed to learn to "fight through" cyber attacks, just as they do now with conventional attacks.
President Obama delivered an identical message during his State of the Union Address on Tuesday night, saying the U.S. needs to be prepared to fight against cyber attacks as much as physical attacks.
The country must integrate "intelligence to combat cyber threats, just as we have done to combat terrorism," the president said.
"No foreign nation, no hacker, should be able to shut down our networks, steal our trade secrets, or invade the privacy of American families," he added.
