The exact number of new nuclear-tipped weapons the Air Force will build through the Ground-Based Strategic Deterrent and Long-Range Standoff Weapon programs could change depending on future treaty negotiations with Russia, according to a Pentagon official. According to the Pentagon's principal director for nuclear and missile defense policy, Greg Weaver, “we don't have any idea what our force requirement is going to be” because New START would expire in 2021 without a follow-on agreement, and long-term force structure plans depend...