The maximum altitude for U.S. military jets varies significantly by aircraft type and mission profile, but most modern fighters like the F-22 Raptor and F-15 Eagle have a "service ceiling" of approximately 60,000 to 65,000 feet. At these altitudes, the air is thin enough to allow for extreme speeds while providing enough lift for maneuvering. Specialized reconnaissance aircraft can fly much higher; the Lockheed U-2 "Dragon Lady" and the NASA ER-2 (a civilian variant) routinely operate at altitudes exceeding 70,000 feet, where the curvature of the Earth becomes clearly visible. For historical perspective, experimental aircraft have pushed even further; the rocket-powered North American X-15 reached a record altitude of 354,200 feet (nearly 67 miles) in the 1960s, which is technically sub-orbital space. In 2026, the development of "Hypersonic" vehicles and the integration of the Space Force mean that the boundary between "atmospheric flight" and "space operations" is becoming increasingly blurred for the next generation of military hardware.