Researchers point to steam at North Korean facility . They write that it 's a sign that the reactor is near or in operation . Comment: North Korea said in April it would restart nuclear facility in April .
Researchers point to steam at North Korean facility . They write that it 's a sign that the reactor is near or in operation . North Korea has opened , shut , re-opened , reshut this reactor before . North Korea said in April it would restart nuclear facility in April .