First of all US can't afford a serious full-scale war with Iran, because Iran's response in the Strait of Hormuz and against regional oil infrastructure will devastate US economy.
What we are expecting is a limited 2 week war with Iran that will not escalate to the point when regional oil infrastructure is threatened and enormous damage is done to Western economies.
The probable truth is that US expected such a limited war with Iran since they killed Qasem Soleimani - US knew that Iran's response to his murder could lead to several weeks of war with both sides exchanging strikes.
Americans knew such a limited war could have happened when they bombed Fordow in June 2025.
But since Iran's response to Soleimani murder and bombing of Fordow was limited, such a limited war never happened.
And now Americans are preparing to fight a war they expected in 2020 and 2025 to pressure Iran into submission.
US and Israel tested Iran in 2020 by killing Soleimani and in 2025 by bombing Fordow and Iran's response showed them that Iran's reaction is predictable.
Probably if Iran responded disproportionately in 2020 when Qasem Soleimani was killed and fought a limited war with US in 2020, then neither the 12 Day War in June nor the current escalation could have never happened.
If Iran shows restraint this time, it will invite more strikes in the future.