If State possessed the depth and breadth of wisdom it arrogates to itself in this statement, we would always be automatically successful in everything.
It's funny how they are so confident they can prove a negative.
But history shows diplomacy is pointless when it is not backed up by force. Otherwise WWI, WWII or Korea would not have occurred. Far from obviating the resort to arms, our economic sanctions against the Empire of Japan hastened it since the Japanese saw US naval power as threatening the shipment of oil from Indonesia.
Never forget that Obama effectively took the side of the Iranian regime against democracy advocates in the wake of Iranian elections.