What happens when the U.S. Navy's force structure planning is built on strategic assumptions that are superseded by a change in the Oval Office? In the case of the U.S. Navy, the right answer is to conduct a new force structure assessment, and the Trump administration's recent release of overarching strategic guidance created a question as to whether the Navy would do so. Deputy Chief of Naval Operations for Warfare Systems Vice Adm. William Merz answered that question recently while testifying before the House Armed Services Committee, revealing that the Navy would perform an updated force structure assessment in response to the new National Defense Strategy. This is welcome news, as the current assessment — released in the waning days of the Obama administration — called for a dramatically larger fleet of 355 ships (over the previous 308 ships called for in the assessment released in 2012) without definitive executive branch direction to do so. As I wrote in late 2016, the strategic assumptions the Navy used in its assessment were classified (as is the actual 2017 National Defense Strategy), but the assumptions used by the Navy then were not authoritative. And while I and most navalists applauded the bottom line advocated by the Navy, it was clear that there was an element of outgoing Secretary of the Navy Ray Mabus thumbing his nose at Secretary of Defense Ash Carter (who resisted Mabus' emphasis on shipbuilding) in the 2016 assessment.