China's senior-most general is accused of leaking information about the country's nuclear-weapons program to the U.S. and accepting bribes for official acts, including the promotion of an officer to defense minister, said people familiar with a high-level briefing on the allegations. The briefing—attended on Saturday morning by some of the military's highest-ranking officers—came just before China's Ministry of National Defense made the bombshell announcement of an investigation into Gen. Zhang Youxia, once considered Chinese leader Xi Jinping's most-trusted military ally. That statement gave few details beyond a probe of severe violations of party discipline and state laws.