The US attack on Iraq and the 10 year war it waged there was by its very description extreme. Nearly a million Iraqis died and the entire society was ruined. That doesn't even take into account all the uranium used that has caused mutations and massive issues for the society there.
No, the U.S. Rules of Engagement are not too extreme, because there are many dangers in Iraq and the United States needs to make sure that the situation is under control. Iraq poses a big threat to the United States, and the country needs to make sure that Iraq does not regress to the danger that it was before.