North Korea seems `` not as stable as we thought , '' one analyst says . ` The public airing of the power play under way -- which is highly unusual -- is probably sending shockwaves through North Korea 's leadership cadre . '' The U.S. and South Korean militaries have been conducting joint exercises in the Yellow Sea for months to practice their ability to counter a possible attack from Pyongyang. Jang Song Thaek was married to Kim 's aunt , was vice chairman of the top military body . North Korea state media say Jang was convicted and executed .
North Korea seems `` not as stable as we thought , '' one analyst says . The U.S. and South Korean militaries have been conducting joint exercises in the Yellow Sea for months to practice their ability to counter a possible attack from Pyongyang. Jang Song Thaek was married to Kim 's aunt , was vice chairman of the top military body . North Korea state media say Jang was convicted and executed .