https://crsreports.congress.gov
February 24, 2021
Integrated Air Defense Systems (IADS) and Military Ranges
For as long as aerial warfare has existed, the continual
expansion of offensive air and missile weapons capabilities
has led militaries to develop commensurate defensive
capabilities. These “air defense systems” (also called “air
and missile defense” (AMD) systems) provide surveillance,
tracking, command and control, and weapons delivery
capabilities to battlefield commanders. Historically, AMD
systems were independently operated and managed by each
military service. Gradually, they became more connected,
and today several of these systems can communicate and
operate collectively. This is basis for the concept of an
integrated air defense system, or IADS. According to the
Department of Defense (DOD), an “IADS is not a formal
system in itself, but the aggregate of Service / functional
component and agency AMD systems.”
Considered part of what DOD terms “defensive counterair”
(DCA), an IADS’ purpose is to protect military assets and
vital locations from aerial threats. Conversely, countering
an enemy’s IADS by destroying, suppressing, or otherwise
neutralizing their system is part of what DOD defines as
“offensive counterair” (OCA). The U.S. military tests and
trains to effectively employ an IADS as well as counter an
enemy’s IADS. Training for and conducting DCA and
OCA activities typically requires a significant amount of air
and ground space, along with access to, and control of, the
associated electromagnetic spectrum (see CRS In Focus
IF11155, Defense Primer: Military Use of the
Electromagnetic Spectrum, by John R. Hoehn).
Military “ranges”—defined under 10 U.S.C. §101(e)—that
support IADS generally correspond to large-scale ranges
used for aviation training. These ranges have the required
land, defined airspace (called a “military operations area”
or MOA), and when necessary sea space, available to
employ multiple AMD systems.
DOD states that several of these ranges are now regularly
operating at full capacity to support numerous types of
military units from across the joint force (e.g., aviation
units, marine amphibious forces, special operations forces).
At some locations, non-DOD federal agencies and coalition
partners also make use of these ranges. This has presented a
capacity challenge for the Military Services who schedule
and manage range use. Further exacerbating the issue, DOD
asserts that recent technology increases in IADS
capabilities have necessitated an increase in testing and
training space (i.e., range size). This has led DOD to
request from Congress expansion of, and in some cases
additional access to, certain ranges that could support
“modern IADS” testing and training—along with several
other readiness requirements.
Congress faces the issue of addressing DOD’s request for
additional range space and access at certain locations, as
DOD seeks to fully train for advances in IADS.
What is a Modern IADS?
Potential adversaries like Iran, Russia, and China have
identified airpower as a primary U.S. advantage in military
operations. As a result, several of these nations have
developed sophisticated IADS to counter U.S. military
capabilities. This includes networking multiple types of
ground–based radars (e.g., long-range surveillance radar,
engagement radar) with mobile command posts and air and
space-based capabilities to provide a larger, and more
comprehensive, picture of the battlespace (Figure 1). This
creates a challenge for U.S. forces because there is no
single sensor or missile to neutralize, but rather a
distributed network to contend with.
Figure 1. How a Modern IADS Functions
Source: Adapted from Royal United Services Institute for Defence and
Security Studies report titled “Modern Russian and Chinese Integrated
Air Defence Systems,” January 2020.
Additionally, advances in U.S. and foreign technologies—
particularly in microelectronics and processing power—
have significantly increased the ranges IADS are able to
surveil, track, and engage targets. These are the “modern
IADS” capabilities U.S. forces employ; they are also the
modern IADS threats U.S. forces face.
Selected Foreign IADS Capabilities
For over 10 years, Russia and China have developed
sophisticated anti-access/area denial (A2/AD) systems in an
attempt to prevent U.S. forces from accessing certain areas
and regions. Capabilities of A2/AD systems—which
include IADS—continue to increase, consequently
increasing the distance from which U.S. forces must operate
to avoid detection and potential harm.
One of the most challenging foreign IADS capabilities that
U.S. forces may encounter is the Russian developed S-400
missile system (SA-21 Growler). This weapons system uses
radars with ranges of up to 400 kilometers (~250 miles),
paired with missiles that can reach similar distances. An
