SEOUL, South Korea—South Korea’s military says North Korea has fired at least one unidentified projectile into its eastern waters. South Korea’s Joint Chiefs of Staff on Thursday didn’t immediately provide further details about the launch. The launch came a day after U.S. and South Korean officials said the North fired short-range weapons presumed as cruise missiles into its western sea over the weekend. The North’s weapons demonstrations come amid stalled nuclear negotiations with the United States. Talks faltered after the collapse of Kim Jong Un’s second summit with former President Donald Trump in February 2019 where the Americans rejected North Korean demands for major sanctions relief in exchange for a partial surrender of their nuclear capabilities. The North has so far ignored the Biden administration’s efforts to reach out, saying it won’t engage in meaningful talks with the U.S. unless Washington abandons what Pyongyang sees as “hostile” policies, which clearly …