Which is exactly what Trump said the day he withdrew.
June 1: The president added he will “begin negotiations to re-enter — either the Paris accord, or really, an entirely new transaction — on terms that are fairer to the United States, its business, its workers, its people, its taxpayers. “We are getting out, but we will start to negotiate and we will see if we can make a deal that is fair.”
http://thehill.com/policy/energy-environment/335955-trump-pulls-us-out-of-paris-climate-deal
“begin negotiations to re-enter”
Why re-enter at all?
If Trump doesn’t think global warming is real, why would he consider renegotiating any agreement?