North Korean leader Kim Jong Un and President Donald Trump have signaled their affection for each other so regularly it might be easy to miss rising fears that the head-spinning diplomatic engagement of the past two years is falling apart. Pyongyang has issued increasingly dire warnings to Washington to mind a year-end deadline to offer some new initiative to settle the nations’ decades-long nuclear standoff. Failure could mean a return to the barrage of powerful North Korean weapons tests that marked 2017 as one of the most fraught years in a relationship that has often been defined by bloodshed, deep mistrust and regular threats.
