What are trans-medium UAPs?

“Trans-medium UAPs are unidentified objects observed transitioning between physical mediums — air to water, water to air, space to atmosphere — without the propulsion modification that such transitions require for known platforms. The U.S. statutory definition of UAP in 50 U.S.C. § 3373 was deliberately expanded in 2022 to include trans-medium phenomena.”

Trans-medium UAP are unidentified objects that move between distinct physical mediums — typically air-to-water or water-to-air — without the propulsion modification or hydrodynamic-to-aerodynamic transition that such crossings would require for any known aircraft, missile, or submersible. Congress and the Pentagon's 2022 statutory definition of UAP (codified at 50 U.S.C. § 3373) was deliberately expanded from the original aviation-only 'Unidentified Aerial Phenomena' to 'Unidentified Anomalous Phenomena' specifically to encompass trans-medium events. The All-domain Anomaly Resolution Office's name reflects the same scope expansion — 'all-domain' meaning air, space, surface, and undersea simultaneously. Trans-medium claims appear in several pre-PURSUE Navy reports (most prominently the 2019 USS Omaha 'transmedium' pyramid-shaped clip filmed off San Diego) and in the broader institutional record AARO inherited. The Pentagon's PURSUE catalog itself contains primarily aerial and lunar-surface phenomena to date; AARO has not formally certified any catalog entry as trans-medium-confirmed.