They weren't suggesting that Iran a responsible for the attack. The general was saying that they were taking advantage of what they perceived to be a weakened America to gain control of a major waterway. The general was suggesting to use military force to show that the US is as strong as ever. Basically, he wanted to demonstrate to the world that the US could still protect it's resources. The president told him to get ready to attack, but he wanted to try a diplomatic approach first.