"no matter what the U.S. does diplomatically" - they've only tried ONE tactic: threats and bullying. Iran is becoming a nuclear capable state and the world will have to live with it: the US will mount the same military operation they mounted against North Korea. There is a rational alternative - global nuclear disarmament, including Israel and the US. But an indefinite nuclear monopoly of these powers is totally unrealistic.
Netanyahu condemns West Bank arson attack, calling it 'terror' (Haaretz)
from the article: U.S. strike on Iran likelier than ever, former CIA chief says