SEOUL, South Korea — North Korean leader Kim Jong Un observed major weapons tests and called for the military’s “deadly and destructive offensive posture” to be bolstered, state media reported Friday, as South Korea announced it would drastically boost its drone warfare capabilities. The development comes as tensions remain high on the Korean Peninsula, with Kim pushing to strengthen both nuclear and conventional military capabilities while refusing to return to talks with South Korea and the United States.The tests watched by Kim on Thursday were meant to evaluate the power of a “special mission" warhead for a tactical ballistic missile,...