A former South Korean submarine flotilla commander warned not to underestimate North Korea’s underwater capability, despite it being outdated and seemingly powerless against today’s South Korean and the U.S. naval forces.

During Kim Jong Un’s previous visit to Chongjin Dockyard last year, Kim is known to have ordered the production of more submarines to counter the surrounding nations’ underwater capabilities, Radio Free Asia (RFA) reported Friday.

“The outcome of modern warfare is decided by which country owns more submarines,” RFA’s source in North Hamgyeong Province quoted Kim as saying.

“The future warfare will take place not on land, nor in air, nor on the surface of waters, but under the