Turkey’s defense ministry said on Thursday that Ankara has issued a maritime notice (NAVTEX) requiring Greece to coordinate with Ankara on all research activities in parts of the Aegean Sea that Turkey considers part of its continental shelf. Turkey recently issued a NAVTEX, a legal advisory message to mariners, outlining objections to Greece’s activities in the Aegean Sea that Ankara says violate international law and demanding that it coordinate these. It is the first time Turkey issued the notice without an expiration date. In 1995, the Turkish parliament declared a “casus belli,” or cause for war, if Greece unilaterally extended its waters beyond six nautical miles in the Aegean, a position Athens says violates international maritime law. Greece says the only issue it is prepared to discuss with Turkey is the demarcation of their maritime zones, including continental shelves and exclusive economic zones.