The Chinese government has hacked a US Navy contractor and stolen a large amount of data relating to underseas warfare.

The data was stolen from a project known as Sea Dragon, in addition to a large amount of other data relating to submarine warfare. The exact contractor wasn’t named but they work for the Naval Undersea Warfare Center.

The Sea Dragon project was started in 2012 as a means of reusing existing technologies for “disruptive offensive capabilities,” though little else is known.

The breach is particularly important for the Chinese because they are currently undergoing their own Navy buildup as a way of challenging the US in Asia.

Including in the hack were a number of other pieces of information that give the Chinese a better understanding of the US’s radar and signal capabilities.

Undersea’s warfare is a important area of Naval development for the Chinese as the US’s superior submarine fleet would play an early and decisive role in a potential conflict between the two superpowers.

The data stolen could aid the Chinese in closing the gap between their own fleet and the American’s while also helping to improve their current lacklustre anti-submarine capabilities.

China has been using its cyber warfare technologies to close the military gap with the US for years, stealing information relating to fighter jet projects like the F-35, anti-missile technologies like the THAAD system, certain small navy combat vessels and aerial drone technology.

An agreement between the Obama administration and the Chinese government in 2015 curtailed these sorts of cyber activities by China, but failed to stop them entirely.