Ukraine said Thursday that ships going to Russian-controlled ports on the Black Sea would be treated as possibly carrying military cargo, a day afterRussiaannounced a similar move.Tensions are rising over the Black Sea afterRussiaexited a deal protecting maritime exports from Ukraine."Starting from 00:00 on July 21, 2023, all vessels in the Black Sea heading towardsRussia's seaports and Ukrainian seaports located in the temporarily occupied territories of Ukraine may be considered by Ukraine as carrying military cargo, with all the associated risks," the defense ministry said.Ukraine also said it had prohibited navigation on "the northeastern part of the Black Sea and the Kerch Strait" near Crimea.The moves make navigation in most of the Black Sea perilous for vessels, afterRussiaon Wednesday banned traffic on the northwestern and southeastern parts of the sea.After Ukraine signaled it was ready to continue exports, Moscow said Wednesday it would consider cargo ships traveling to Ukraine through the Black Sea potential military targets.