My uncle was with the Air Force and was some sort of tech guy (radios, radar?) and was on Iwo Jima a couple days after they landed trying to get the runways going.
“Wow? Just two days?”
“Yeah - but the Marines had cleared all the Japs out. Well, sometimes they would snipe at us from the other side of the runway, but they were lousy shots.”
He stayed in that line of work and worked with NASA, etc.
However, it took another five weeks to secure the island, so there was not a lot they could do with it.
Almost 7,000 USA dead in the battle, so it was never completely safe until the war ended.
Also, Iwo was never utilized at the level they had planned.
It was supposed to launch fighter escorts for B-29 bombers, plus create an emergency landing site for damaged bombers that could not make it back to their home base. Those two things never really happened in large numbers.
It did poke a hole in Japans radar coverage, naval surveillance, and naval supply chain, plus it killed 21,000 Japanese soldiers, so it was clearly a high value outpost for the Japanese military command.