The aerostats used in the TARS system are large fabric envelopes filled with helium that can rise to an altitude of 15,000 feet (4,600 m) while tethered by a single cable.

The aerostat consists of four major parts or assemblies: the hull and fin, windscreen and radar platform, airborne power generator, and rigging and tether; they are kite balloons obtaining aerodynamic lift from relative wind and buoyancy from being lighter than air.

The 420K's envelope shape, fin design, and cable attachment points are further optimized for high aerodynamic stability and easy ground handling.

The overall responsibility for this program fell to Customs and the Coast Guard, until the US Congress in 1991 and 1992 transferred management to the US Department of Defense, with the Air Force as executive agent.

[citation needed] Since 2003 some 66 Persistent Threat Detection System (PTDS) aerostats have been put into action in Iraq and in Afghanistan for protecting convoys in transit and providing intelligence on enemy troop movements.

[6] However, the U.S. Customs and Border Protection (CBP) assumed responsibility the Tethered Aerostat Radar System (TARS) project and its funding since fiscal year 2014.

[7] The Philippine Navy (PN) formally received a 28M Class Tethered Aerostat Radar System (TARS) from the United States government in a turn-over ceremony on August 22, 2017 at the Naval Education and Training Command (NETC) inside Naval Station Leovigildo Gantioqui in San Antonio, Zambales.

For security and safety reasons, air space around aerostat sites is restricted for a radius of at least two to three statute miles and an altitude up to 15,000 feet (4,600 m).

The secondary mission is to provide North American Aerospace Defense Command with low-level surveillance coverage for air sovereignty in the Florida Straits.