**US strike on Mexico by December 31 faces low trader-implied odds due to sustained Mexican sovereignty assertions and bilateral security cooperation that has so far channeled tensions into joint operations rather than unilateral action.** President Trump has designated major cartels as foreign terrorist organizations and signaled potential strikes against fentanyl labs and leadership, while Mexico’s President Claudia Sheinbaum has repeatedly ruled out any U.S. military presence on Mexican soil. A late-September border shooting incident involving U.S. Coast Guard personnel prompted mirrored troop deployments and “Operation Mirror” coordination along the Rio Grande, but Mexico has requested evidence and rejected escalation. U.S. actions have included anti-drone measures and reported strikes on vessels in international waters, yet no qualifying air, drone, or missile strikes on Mexican territory have occurred. Ongoing diplomatic and intelligence channels, combined with Mexico’s constitutional barriers and public opposition to intervention, continue to anchor the low probability of a qualifying strike before year-end.