Its path can be adjusted during flight, either by automatic self-contained controls or remote human control. Guided missiles are powered either by rocket engines or by jet propulsion . The V-2, which was powered only during the first part of its flight, was the world's first operational ballistic missile with a powered launch followed by an unpowered parabolic trajectory, sometimes guided by radio. They have become the key strategic weapon of modern warfare and a crucial, and much used, tactical weapon.
Aerodynamic missiles are of four types.
The key U.S. offensive ballistic missiles are the Minutemen ICBMs, which are launched from silos, and the submarine-launched Tridents, which replaced the earlier Polaris and Poseidon.