From the Document: "The Marine Corps operates a fleet of helicopters to provide transportation for the President, Vice President, and other senior officials. These aircraft are known as 'Marine One' when the President is aboard. The VH-92 program is intended to provide 23 new helicopters to replace the current fleet of aging VH-3D and VH-60N presidential helicopters. [...] An earlier replacement program, the VH-71, was terminated in 2009 following substantial cost growth and schedule delays. Following that termination, in FY2010, the Obama Administration proposed a new presidential helicopter program, called the VXX Presidential Helicopter Program, which became today's VH-92 program. Of the 23 VH-92 helicopters the Marine Corps plans to acquire, six were acquired through research and development funding for development and test prior to 2019, and four of those are to be outfitted to join the operational fleet. Congress appropriated $649 million for six production VH-92s in FY2019 and $641 million for another six in FY2020. The final five were included in a $578 million appropriation in FY2021. The total program acquisition cost, including development and procurement, is projected at $4.9 billion, 5.6% less than initially estimated in 2014."
CRS In Focus, IF11598
Congressional Research Service: https://crsreports.congress.gov/