Boeing’s decision to drop out of the bidding for a next-generation missile contract it believes is weighted in a rival’s favor may force the Pentagon to reconfigure the $85 billion weapons project.

The Ground-Based Strategic Deterrent program is intended to be a successor to about 400 existing Minuteman III intercontinental ballistic missiles, introduced in the 1960s, and the Air Force said earlier this month it hoped to award a contract to either Boeing or Northrop Grumman in 2020. The new missiles are a vital piece of President Trump’s goal of modernizing the U.S. nuclear triad, which also includes sea- and air-based weapons.