Sino-Russo missile threats key new US OTH radars

For the first time in at least 20 years, the US plans to build and install over-the-horizon (OTH) radar systems – four of them. At the same time, Canada plans to acquire two additional systems for its northwest.

The resulting six systems are aimed at providing an early warning capability to detect the launch and track of Russian and Chinese long-range cruise missiles – although the US does not yet have any clear plan on how to shoot them down.

Russia has faced US long-range cruise missile threats since the late 1970s and has updated its OTH radars – the latest, called Kontaine, in 2013.

A cruise missile is a form of unmanned aerial vehicle (UAV) that is powered by a turbine jet engine. Cruise missiles can carry conventional warheads or small nuclear weapons. Cruise missiles can be used on the tactical battlefield or in long-range versions for delivering nuclear weapons on high-value targets. The Russians are using cruise missiles in the Ukraine war, and the Ukrainians are using the Franco-British Storm Shadow.

The US Tomahawk cruise missile was originally designed as a cheap alternative to manned bombers for penetration of Soviet Union defenses. The Tomahawk could fly to the target at very low altitudes that created a problem for the Soviet defenders.

Today, the nuclear warheads for Tomahawk are in storage, although the Russians have raised concerns that the nuclear warheads could be reintroduced surreptitiously and could be launched from US bomber aircraft, from sea vessels (surface ships and submarines) or from ground locations in Romania and Poland.

AEGIS cruisers and destroyers and AEGIS Ashore in Romania use the Mk-41 launcher, capable of launching conventional and nuclear-tipped Tomahawks.

Detecting long-range cruise missiles is a challenge, even when they are launched from aircraft. OTH radar systems are specialized radar technology that can “see” over long distances and detect threats even at low altitudes.

In recent years, old OTH radars in the United States were replaced by satellites, but satellites cannot always track low-flying small weapons because of radar “clutter’ close to the ground, whether land or sea.

Computers running fast Fourier transform algorithms can sort out some of the ground clutter, but satellites typically operate in radar bands where small targets are difficult to extract from induced noise.

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