So assuming they are what you say they are,
Nothing to assume... the facts speak for themselves. He's on record all over the place, Reuters, AP, UPI, etc. etc. claiming the holocaust never happened, and advocating that Israel be wiped off the face of the earth. Any cursory search will show that these are anything but assumptions--they are facts.
what motivation do they have to stop their nuclear program? Why should they stop it, from their point of view?
Perhaps they might just realize that this could wind up potentially very ugly. The fact is that for a nation as obviously full of ethnic hatred as their leadership appears to be, a nuclear weapon is, no pun intended, a bomb simply waiting to go off. Of course that would be presuming they were capable of rational thought.
A2K