Hackers have been targeting American nuclear facilities since May: Homeland Security and FBI
Some 331 kilograms of plutonium will be sent by ship from Japan to a nuclear facility in South Carolina by the end of March (AFP Photo/Kenzo Tribouillard)

Homeland Security and the Federal Bureau of Investigations released a joint report at the end of last month issuing a "urgent" alert about hackers penetrating the networks of nuclear facilities.

According to the New York Times, who obtained the June 28 joint report Thursday, hackers have targeted both nuclear and manufacturing facilities, such as the Wolf Creek nuclear power plant in Burlington, Kansas, who claimed their operations systems have not been compromised.

It's unclear whether the hacks were attempts at stealing nuclear or industrial codes or part of an attempt to "cause destruction."

This publication of intelligence from the joint FBI/Homeland Security report comes after late June report claiming Homeland privately warned businesses about potential hacks of nuclear or energy firms. It also comes just over six months after a Vermont electric utility was hacked by Russian operatives in late 2016.