Several months ago North Korea had a huge conventional explosion that was big enough that some felt it could have been nuclear.
It is also reported that if N.K. has nukes, they only have enough material to make 7-9 bombs.
So... Was this a bluff on North Korea's part? Or is the U.S. claiming it likely wasn't a nuke a bluff to get N.K. to do another test and use up their remainning store of explosives?