The new Sentinel nuclear weapons program is 81% over budget and is now estimated to cost nearly $141 billion. But Pentagon officials are moving forward with the program, saying that given the threats from China and Russia, they do not have a choice. The Sentinel program is the first major upgrade to the land-based component of the nuclear triad in more than 60 years and replaces the aging Minuteman III intercontinental ballistic missile. The high cost overrun triggered a Pentagon review. To move forward, the program will scale back on some items, including modernization plans for the launch facilities.