The US military website reported that in order to greatly strengthen its offensive and defensive capabilities in the Western Pacific region, the Pentagon plans to build a tactical mobile over-the-horizon radar (TACMOR) in Palau. The U.S. Department of Defense recently announced that the initial construction of the equipment has been awarded to the corresponding contractor for infrastructure construction and is expected to be completed in mid-2026.
The article said that traditional "sky wave" or "backscatter" over-the-horizon radar usually consists of a large antenna array scattered over an area, and the transmitting and receiving sites are usually staggered in location. Over-the-horizon radar has the ability to detect targets at extreme ranges beyond the so-called " radar horizon". Typically, the detection range of radar is affected and limited by the curvature of the earth. Over-the-horizon radar overcomes this key limitation, but it also has some major shortcomings.
Skywave type over-the-horizon radar does this by bouncing radio waves from the ionosphere into a coverage area, where they hit the target and return to the receiving station in the same way. The other is to use the "surface wave" concept, which takes advantage of the ocean's conductive salt water and the tendency of radio waves to bend around curves under the "Norton principle" to spread radar waves over the horizon. These are often called "ground waves" but have a much smaller range than sky wave types, but since they don't rely on bouncing off the ionosphere they don't have big blind spots either.
How Sky Wave Radar Works
Surface Wave Radar vs. Conventional Radar Range Comparison Chart
As mentioned previously, these systems are not as accurate or as resolution-like as many line-of-sight systems, and their static nature makes them vulnerable to attacks, and atmospheric and space weather conditions also play a significant role in their effectiveness from time to time. But despite this, they can still provide wide-area situational awareness and key sensor prompts and early warnings. Through the processing of high-speed computers and artificial intelligence software, their low-fidelity data can prove to be very enlightening and actionable. The article believes that this is very valuable for monitoring the South China Sea and stealth targets from China.
reports said that Palau’s modern over-the-horizon radar will be able to support space-based and land-based sensors and weapon systems, which can be used to provide potential prompts and early warnings for incoming hypersonic weapons, cruise missiles, ballistic missiles, enemy aircraft and ships. Most importantly, this radar allows for constant monitoring of a specific area.
According to the U.S. Air Force's 2023 fiscal year budget justification document, the size of the tactical maneuver over-the-horizon radar will be one-quarter of the traditional over-the-horizon radar and will be stationed in the Republic of Palau in order to enhance situational awareness of air and maritime activities.
The emergence of over-the-horizon radars only underscores the Pentagon’s recent increased emphasis on providing a persistent U.S. military presence in the Indo-Pacific. Palau itself is becoming particularly strategic as the United States focuses on preparing for a potential future high-end conflict with Chinese forces in the region, while also working to counter the threat posed by the missile arsenals of adversaries such as North Korea.
reported that Palau is an independent country with a long history with the United States under the 1994 Compact of Free Association (COFA) agreement, which governs military relations between the two countries. The U.S. military has been using Palau extensively for various military exercises over the years, including this year's Valiant Shield 2022. During the exercise, Palau launched the Patriot surface-to-air missile system for the first time. The Air Force also used this opportunity to conduct testing and operational exploration of the A-10 attack aircraft and the C-130 transportation authority.
One of the 23rd Wing's A-10Cs parked at Romante Mettuhel International Airport in Palau. See another one on the left.Image source: U.S. Air Force
At the same time, the U.S. military has carried out similar activities in Guam, Tinian, and other islands and areas in the region. These islands have become hot spots for the expansion of U.S. military infrastructure in modern times, but the development of Palau's over-the-horizon radar further shows that the U.S. military's focus in the Pacific region is undergoing an increasing shift.
