The officials said hackers working for the Iranian government or a proxy group with approval from Iranian leaders are responsible for penetrating the unclassified Navy computer network.
US officials said they do not believe information of significant value was lifted, though the potency of such a cyberattack that accessed military data set off alarms at the Pentagon, the Wall Street Journal reported.
Iran’s cyber abilities have increased gradually, gaining further recognition from the US military, according to anonymous officials.
“Their ability to also play in this [cyber] sandbox compounds that concern,” a US official said.
Defense Secretary Chuck Hagel and Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey were briefed on the infiltration and how the Pentagon is boosting its network strength. Congress has also been briefed on the hack, officials said.
Previous Iran-backed hacks and surveillance efforts have gone after US banks and energy industry computer networks.
The allegations occur as the US and Iranian governments have increased negotiations over Iran’s nuclear program. US President Barack Obama and Iranian President Hassan Rouhani spoke on Friday, after both leaders delivered speeches this week before the United Nations General Assembly in New York.
Iranian officials did not return requests for comment, the WSJ reported.
The US led a cyberattack — dubbed ‘Olympic Games’ — on Iranian uranium enrichment facilities during the Bush and the Obama administrations, the New York Times reported last July. The program included a collaboration with Israeli hackers to develop the Stuxnet computer worm, which was used to infect Iranian computer networks and damage hundreds of centrifuges at the Natanz enrichment facility.