Tensions in U.S.-Mexico security cooperation, centered on cartel activity and fentanyl flows, have produced recent diplomatic friction and limited border deployments, yet both governments continue coordinated operations that have driven southwest encounters to historic lows. Mexican officials have repeatedly rejected any U.S. military presence on sovereign territory, while U.S. actions remain confined to enhanced patrols, drone restrictions, and joint training rather than cross-border strikes. This pattern of managed pressure alongside deep economic interdependence under frameworks like USMCA underpins trader consensus that no invasion will occur in 2026. Realistic shifts could stem from major border incidents, abrupt policy reversals, or rapid escalation in cartel violence, though current evidence shows no trajectory toward full-scale intervention.