A new report shows North Korea has more submarines than South Korea but that the level of threat posed by the North’s submarines is not serious.

According to the report by Mackenzie Eaglen and Jon Rodeback, both researchers at the Heritage Foundation, North Korea has 22 outdated conventional attack submarines and numerous mini-submarines, adding that it is unknown how many of them are serviceable.

The report said that while the North’s submarines could theoretically threaten merchant shipping and unsophisticated naval combatants, they are not viewed as serious threats in sea control operations.

The report said South Korea currently has 12 submarines and plans to increase its fleet to 27 by 2020.