The RQ-180 appears to be a follow-on to the Joint Unmanned Combat Air Systems project which was cancelled in late 2005 when the United States Navy (USN) wanted a carrier-based aircraft (which led to the UCAS-D) while the United States Air Force (USAF) wanted a larger, long-range global strike platform.
The RQ-180 was secretly funded through the USAF's classified budget.