Donald Trump Kim Jong-un 2

President Trump and Chairman Kim Jong-un have bested their doubters and not only smiled and shaken hands but have signed off on a document committing to the Holy Grail of contemporary diplomacy -- the denuclearisation of the Korean Peninsula.

Both will be able to go home with a win in their pocket and great visuals for their respective masses. But what comes next, and how easily is this hard work undone?