from wikipedia: Territorial sea, as defined by the 1982 United Nations Convention on the Law of the Sea,[2] is a belt of coastal waters extending at most 12 nautical miles (22 km; 14 mi) from the baseline (usually the mean low-water mark) of a coastal state. The territorial sea is regarded as the sovereign territory of the state

I would guess that there's oil or shipping lanes or aircraft bases that they would want.