In the first case prosecuted under Japan's 2009 antipiracy law, two Somali men pleaded guilty Tuesday in Tokyo District Court to charges of boarding and attempting to hijack a Bahamas-registered tanker operated by a Japanese shipping company.

The ship, sailing in the Indian Ocean off Oman, came under attack in March 2011.

While acknowledging the attempted piracy, defense lawyers questioned the legitimacy of prosecuting the case in Japan, rather than where the crime was committed. They also argued that neither the vessel's registry nor any crew on board were Japanese.