The way I envision it, there will be a sudden and undeclared massive air strike against the Iranian terrorist regime nuclear facilities and this will take 5-7 days. Depending on how the Iranian responds the war will escalate tremendously from our side. If Iran hits oil tankers, or oil infrastructure in other Gulf states, or hit our Navy ships, or our bases in the area, then the air and naval war will expend to destroy the terrorist regime military infrastructures, command and control centers, and its refining capacity but not the oil and gas production facilities. This will last for 3 to 4 weeks.
The terrorist regime in Tehran will not survive this air and naval war, they will be very weakened, the Iranian people will rise against them and this time unlike the 1991 Gulf War against Saddam, the American military will support the Iranian people in term of Air support and destruction of what ever military left loyal to the terrorist mullahs that is going to oppress the people of Iran.