Complex sentence: The longer breakout time would be in place for at least ten years; after that point, the breakout time would gradually decrease, and by the fifteenth year, the Obama Administration says it would return to the pre-JCPOA status quo of a few months.
Split into simpler sentences: The longer breakout time would be in place for at least ten years; after that point, the breakout time would gradually decrease. By the fifteenth year, U.S. officials state that the breakout time would return to the pre-JCPOA status quo of a few months.