The B-2 is 1980's stealth technology and the Russians and Chinese have ability using satellite based technology to see the flight of the bombers as soon as they takeoff and they are at or near to the point that they can use that satellite technology to shoot down stealth bombers. The destructive power of the B2 is tremendous with up to 12-16 Nuclear bombs. But with just conventional bombs it carries 80 500lb guided bombs. The 59 tomahawk missile we fired at a single airbase in Syria have a 1,000 pound payload and the damage was so light that the airbase was back in action a day after the attack. So roughly one B2 is like 40 Tomahawk missiles-- less than we fired in Syria. So we need to use a good portion of our 20 B2's we have, shipboard Tomahawks, and F35's armed with rockets. But we do not know where the targets are and NK has heavily fortified their facilities. With the advance warning they will have, they can launch a counter attack before the B2' reach NK.