A source told Reuters on Tuesday that a cargo ship loaded with grain has set sail from the Ukrainian port of Chornomorsk on the Black Sea for the first time since the collapse of the grain agreement, testing Ukraine's ability to open its maritime ports for export. Ukraine announced last month a "humanitarian corridor" in the Black Sea for ships trapped in its ports since the start of the war in February 2022, circumventing the blockade imposed after Russia withdrew from the agreement that allowed Kyiv to export its grain.