In 1942 and early 1943, US submarines posed little threat to Japanese ships, whether warships or merchant ships. They were initially hampered by poor torpedoes, which often failed to detonate on impact, ran too deep, or even ran wild. As the US submarine menace was slight in the beginning, Japanese commanders became complacent and as a result did not invest heavily into ASW measures or upgrade their convoy protection to any degree to what the Allies in the Atlantic did. Often encouraged by the Japanese not placing a high priority on the Allied submarine threat, US skippers were relatively complacent and docile compared to their German counterparts, who understood the "life and death" urgency in the Atlantic.