A possible deal between Russia and Ukraine that would have ensured the safe movement of cargo ships in the Black Sea fell through at the last moment in March after Kyiv abruptly withdrew from negotiations, Reutersreported Monday, citing four anonymous sources familiar with the matter. The talks, which Turkey mediated after “nudging” from the United Nations, reportedly took place over the course of two months and were due to be announced by Turkish President Recep Tayyip Erdogan on March 30. “At the very last minute, Ukraine suddenly pulled out and the deal was scuttled,” one of the sources was…