Quote from article linked below:

A senior Trump administration official told NewsNation that they had analysis showing that if the United States “sat back and waited to get hit first,” the amount of casualties and damage would be substantially higher than if the U.S. acted preemptively before Iran launched its own strikes. This is the intelligence picture that Jennings’ sources were describing — not a hypothetical threat or a distant danger to be managed through more diplomacy, but an imminent, planned attack that American and Israeli forces moved to intercept on the ground before it could launch.

A senior Trump administration official confirmed to CNN that they believed Iran was preparing to potentially launch preemptive missile strikes, and that this assessment was a direct factor in Trump’s decision to initiate military action. The official added that the intelligence showed Iran potentially intended to use its missile arsenal simultaneously with any response to U.S. action — meaning the window to act was not measured in days, but hours. The same official said the president “frankly had no choice” but to act, because Iran had refused to engage seriously on ballistic missiles during negotiations and had met American offers of a civil nuclear program with what officials described as “games, tricks, and stall tactics.”