At North Korea’s grand reveal of its largest warship to date last week, leader Kim Jong Un declared that the DPRK’s naval forces will now patrol not only coastal waters but also what he called “the waters of middle demarcation lines” with other countries.

While state media has yet to define the terminology, it appears to represent a fresh challenge to the Northern Limit Line (NLL), the de facto maritime border that has separated the two Koreas since the 1953 armistice, raising the risk of new tensions in historically contested waters.

Experts told NK Newsthat the ambiguous term likely