The trigger for President Trump's strikes on Iran was the downing of a U.S. helicopter, but behind the scenes Trump had been growing more and more frustrated over nearly two weeks of waiting for an Iranian response to his latest offer that still has not arrived. Why it matters: The strikes on Tuesday evening were intended to restore some leverage, but be calibrated such that no one would be killed and the possibility of a deal would not be foreclosed, a senior U.S. official told Axios. At the s