out (example: American Ground-Based Midcourse Defense (GMD), Chinese SC-19 & DN-series missiles, Israeli Arrow 3 missile). Advantages: Extended decision/intercept time (the coast period through space before reentering the atmosphere can be several minutes, up to 20 minutes for an ICBM). Very large geographic defensive coverage; potentially continental. Disadvantages: Requires large, heavy anti-ballistic missiles and sophisticated powerful radar which must often be augmented by space-based sensors. Must handle potential space-based decoys. Terminal phase Intercepting the missile after it reenters the atmosphere (examples: American Aegis Ballistic Missile Defense System, Chinese HQ-29, American THAAD, American Sprint, Russian ABM-3 Gazelle) Advantages: Smaller, lighter anti-ballistic missile is sufficient. Balloon decoys do not work during reentry. Smaller, less sophisticated radar required. Disadvantages: Very short intercept time, possibly less than 30 seconds. Less defended geographic coverage. Possible blanketing of target area with hazardous materials in the case of detonation of nuclear warhead(s). Intercept location relative to the atmosphere Missile defense can take place either inside (endoatmospheric) or outside (exoatmospheric) the Earth's atmosphere. The trajectory of most ballistic missiles takes them inside and outside the Earth's atmosphere, and they can be intercepted in either place. There are advantages and disadvantages to either intercept technique. Some missiles such as THAAD can intercept both inside and outside the Earth's atmosphere, giving two intercept opportunities. Endoatmospheric Endoatmospheric anti-ballistic missiles are usually shorter ranged (e.g., American MIM-104 Patriot, Indian Advanced Air Defence). Advantages: Physically smaller and lighter Easier to move and deploy Endoatmospheric intercept means balloon-type decoys won't work Disadvantages: Limited range and defended area Limited decision and tracking time for the incoming warhead Exoatmospheric Exoatmospheric anti-ballistic missiles are usually longer-ranged (e.g., American GMD, Ground-Based Midcourse Defense). Advantages: More decision and tracking time Fewer missiles required for defense of a larger area Disadvantages: Larger/heavier missiles required More difficult to transport and place compared to smaller missiles Must handle decoys Countermeasures to missile defense Given the immense variety by which a defense system can operate (targeting nuclear-armed intercontinental ballistic missiles (ICBMs), tactical, and theater missiles), there are some unarguably effective exoatmospheric (outside the Earth's atmosphere) countermeasures an attacking party can use to deter or completely defend against certain types of defense systems, ranges of ACBM's, and intercept locations. Many of defenses to these countermeasures have been implemented and taken into account when constructing missile defense systems, however, it does not guarantee their effectiveness or success. The U.S. Missile Defense Agency has received scrutiny