Abstract; The international collaboration designing and constructing; the Deep Underground Neutrino Experiment (DUNE) at the Long-Baseline; Neutrino Facility (LBNF) has developed a two-phase strategy toward; the implementation of this leading-edge, large-scale science; project. The 2023 report of the US Particle Physics Project; Prioritization Panel (P5) reaffirmed this vision and strongly; endorsed DUNE Phase I and Phase II, as did the European Strategy for; Particle Physics. While the construction of the DUNE Phase I is well; underway, this White Paper focuses on DUNE Phase II planning. DUNE; Phase-II consists of a third and fourth far detector (FD) module, an; upgraded near detector complex, and an enhanced 2.1 MW beam. The; fourth FD module is conceived as a “Module of Opportunity”, aimed; at expanding the physics opportunities, in addition to supporting; the core DUNE science program, with more advanced technologies. This; document highlights the increased science opportunities offered by; the DUNE Phase II near and far detectors, including long-baseline; neutrino oscillation physics, neutrino astrophysics, and physics; beyond the standard model. It describes the DUNE Phase II near and; far detector technologies and detector design concepts that are; currently under consideration. A summary of key R&D goals and; prototyping phases needed to realize the Phase II detector technical; designs is also provided. DUNE's Phase II detectors, along with the; increased beam power, will complete the full scope of DUNE, enabling; a multi-decadal program of groundbreaking science with neutrinos.
