Diplomatic genius, is Always dependent, on the good will & faith, of Both adversaries. The last ones, 'imho' were: Abe Lincoln, Gen. U.S. Grant; And General, Robert E. Lee. 'Kissinger' ultimately turned out to be a flawed diplomatic 'genius'; Thanks, to Vietnam.
 
After those 'titans'; I suspect, that the rest of the 'field'.. are merely well-intentioned aspirants; As the disputes, have grown more intractable; Save, for how 'Vietnam' ended --