USML Category XI: sonar, radar and electronic warfare

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1. Military electronics, part one

Category XI of the United States Munitions List (USML) is headed "Military Electronics" (22 CFR 121.1). Paragraph (a) covers electronic equipment and systems not included in Category XII, in twelve numbered entries, one of them reserved. This piece covers the first four, which deal with underwater systems, radar and electronic warfare. Communications, sensors, intelligence systems and components are covered in Category XI, communications, sensors and components.

All four entries carry an asterisk (22 CFR 121.1). That designates them as Significant Military Equipment under the International Traffic in Arms Regulations (ITAR), and technical data for their manufacture or production takes the same status (22 CFR 120.10).

2. Underwater systems

Paragraph (a)(1) covers underwater hardware (22 CFR 121.1). It includes active or passive acoustic array systems able to process in real time and to survey or detect, and also track, localize, classify or identify, vessels, submarines, undersea vehicles, torpedoes or mines. They are caught if they have multi-static capability, an operating frequency less than 20 kHz, or an operating bandwidth greater than 10 kHz. Single acoustic sensor systems that distinguish non-biologic tonals and locate the source are included, with tonals meaning discrete frequencies from man-made objects. Non-acoustic systems performing the same tracking and identification functions are included too.

The entry also covers acoustic modems and communications equipment with real-time adaptive compensation or low probability of intercept (22 CFR 121.1). Low and very low frequency modems and communications equipment specially designed for submarine communications are listed. So are autonomous systems enabling cooperative sensing and engagement by fixed or mobile autonomous underwater vehicles. Paragraph (a)(2) covers underwater acoustic countermeasures and counter-countermeasures.

3. Radar

Paragraph (a)(3) lists radar by capability rather than by platform (22 CFR 121.1). Airborne radar that maintains the positional state of objects of interest through time is covered, other than for weather. A note releases airborne radars that meet three tests together. They cannot detect a 1 square meter target beyond 8 nautical miles, have an update rate of not more than 1Hz, and use a design placed under the Export Administration Regulations (EAR) by a commodity jurisdiction determination. Synthetic aperture radar with image resolution better than 0.3 m, and inverse synthetic aperture radar, are covered. So is synthetic aperture radar using coherent change detection with geo-registration accuracy better than 0.3 m, although certain concealed object detection equipment operating between 30 GHz and 3,000 GHz is excluded.

Surveillance radars are caught by performance thresholds (22 CFR 121.1). They include ocean surveillance radar above stated power-aperture or bandwidth and rotation figures, and air surveillance radar detecting a 1 square meter target at 85 nmi or more. Radar that geolocates targets with a target location error of 10 m or less at ranges greater than 1 km is covered too. So is instrumentation radar for test facilities, and radar with pulsed operation and electronic steering of the transmit beam in both elevation and azimuth. A note releases low-power versions of the last type, at 550 watts peak or less, where a commodity jurisdiction determination has placed the design under the EAR.

Other radar entries turn on function (22 CFR 121.1). They cover ballistic tracking to launch or impact points, active protection and missile warning radar, over the horizon sky-wave radar, and radar detecting moving objects through a physical obstruction. Radar with advanced clutter processing, electronic protection beyond basic techniques, electronic attack or electronic support modes, or non-cooperative or automatic target recognition is listed. So are radars that guide interceptors, use low probability of intercept waveforms, send and receive communications, or discriminate warheads from debris. Passive bi-static radar using commercial broadcasts and radar target generators for controlled radars complete the list.

A note to the radar paragraph excludes three things (22 CFR 121.1). They are systems that need aircraft transponders to meet the control parameters, precision approach radar conforming to ICAO standards with the stated antenna types, and radio altimeters conforming to FAA TSO C87. Radar specially designed for certain Category IV missiles or Category VIII unmanned aircraft carries the (MT) annotation where the vehicle can deliver at least 500 kg to at least 300 km.

4. Electronic warfare

Paragraph (a)(4) covers electronic combat, also called electronic warfare (22 CFR 121.1). The first entry is electronic support systems that search for, intercept, identify or locate sources of electromagnetic energy, specially designed for immediate threat detection, recognition, targeting, planning or future operations. A note says electronic support provides situational awareness, cueing, targeting, electronic order of battle planning, and electronic, communications or signals intelligence.

The second entry is systems that detect and automatically discriminate acoustic energy from weapons fire, such as gunfire, artillery or rocket propelled grenades (22 CFR 121.1). They must locate the fire or its direction in less than two seconds and be able to operate on the move, on personnel, vehicles, vessels or aircraft. The third entry is systems specially designed to introduce extraneous or erroneous signals into radar, seekers, radio or navigation receivers, or otherwise hinder adversary electronics. GNSS anti-jam and anti-spoofing systems are excluded. The examples given are electronic attack, countermeasure and counter-countermeasure equipment, jamming and counter-jamming.

Several entries in paragraph (a)(4) apply regardless of platform (22 CFR 121.1). The weapons fire detection entry, for example, lists personnel, land vehicles, sea vessels and aircraft as places where the system may operate while in motion.

5. Low probability of intercept

Several entries turn on low probability of intercept, which a note defines for the whole category (22 CFR 121.1). It is a class of measures that disguise, delay or prevent the interception of acoustic or electromagnetic signals. The techniques can involve power or energy management, frequency variability, out-of-band operation, low side lobe antennas, complex waveforms and complex scanning. The same idea is also called low probability of detection or identification.

Technical data, meaning information such as drawings and instructions required to produce, operate or repair them, is controlled with the hardware (22 CFR 120.33).

Key terms

Tonals	Discrete frequencies in the broadband and narrowband spectra coming from man-made objects.
Electronic support	Systems that intercept and locate emissions to support threat detection and targeting.
Low probability of intercept	Measures that disguise, delay or prevent interception of acoustic or electromagnetic signals.
Synthetic aperture radar	Imaging radar, controlled here at image resolution better than 0.3 m.
Weapons fire detection	Acoustic systems that locate gunfire in under two seconds while on the move.

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This page describes public United States government programs for general information. It is not legal, regulatory or procurement advice, and it does not address the facts of any particular case.

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