I know it's complicated but why not make Iraq a state?

After the start of the United States there was a theory called manifest destiny. This theory was that the United States was destined to stretch from the east coast to the west coast. Then the United States acquired Puerto Rico, Hawaii, Virgin Islands, Guam and a few other territories I can't think of. At this point Congress decided not to expand territories any further. A big reason is the United States became a nation by fighting colonialism and the United States in a way was doing the exact same thing many years later by expanding territories.