As during the first 1941 campaign, the Soviet Navy sent submarines against the Axis supply lines along the western coast of the Black Sea. A number of neutral Turkish vessels were also attacked near the Bosporus area, resulting in the Struma disaster. Once again, Axis defenses primarily consisted of Romanian-laid fields of mines: 5000 mines were laid (both anti-submarine and floating), the Soviet Navy possessed 34 submarines including 14 of new construction but only 20 were operational ready. German U-boats began operating in the Black Sea during late 1942, without scoring any hits while the Romanian submarine Delfinul departed for her final patrols.