Kim Jong Un has been playing to President Donald Trump’s narcissistic personality. Agreeing to meet and shake hands while continuing to build his nuclear program has allowed Trump to claim his nonexistent negotiating superiority. Trump claims President Barack Obama tried unsuccessfully to negotiate a similar breakthrough. That never happened. Also, Trump's claim that the U.S. would have now been at war if not for him has no basis.
Instead of praising Kim and expressing a joint loving relationship, Trump should be emphasizing his repugnant reputation as a world leader in instigating internal crimes against humanity. That should be a significant element in any negotiating strategy. That includes any nuclear negotiations. In the meantime, strict economic sanctions should remain in place to deter his nuclear aspirations.
The same as past U.S. presidents, Trump should refuse to deal with Kim for any reason until he agrees to desist in his reign of terror, including his inhuman support of prison gulags, barbarous executions and abhorrent reign of human right violations. All of this is in direct contradiction to American values.