North Korean leader Kim Jong-un has criticized South Korea’s push to build a nuclear-powered submarine, calling it an offensive move that seriously infringes on his country’s security and maritime sovereignty. 

The North’s state-run Korean Central News Agency said Thursday that Kim voiced the stance when he personally inspected a site where the North is building an 87-hundred-ton nuclear-powered strategic guided missile submarine.

Kim said the South’s submarine development plan, which resulted from an accord with the U.S., is a security threat that must by all means be addressed, saying the move will worsen instability on the Korean Peninsula. 

The North Korean leader went on to say that Pyongyang has no plans to change its national security policy or its principle of deterring the enemy. 

He said it should be made clear that enemy forces that threaten the North’s strategic sovereignty will pay dearly and will be met with retaliation if they attack. 

The term “nuclear-powered strategic guided missile submarine” apparently refers to a nuclear-powered submarine carrying a strategic guided missile.