On 28 February 2026, the United States and Israel launched a joint military campaign against Iran, whose subsequent strikes targeted all GCC states. While US commanders considered the regional air and missile defence network validated in combat, the GCC continued to call for greater military integration and completion of its joint ballistic missile alert system. This apparent gap reflects the architecture’s hybrid nature: national capabilities coexist with GCC mechanisms, bilateral agreements and US functions. Although information-sharing and operational coordination have improved, authority over forces and resources remains largely national. The system enhances immediate protection but creates dependencies on shared alerts, data, command, interceptors and maintenance. Its resilience therefore depends on sustaining these functions under prolonged, high-intensity consumption.