The United States and Japan are considering joint development of a defense system capable of hitting hypersonic weapons, particularly those in flight while flying. The two countries that are already collaborating on ballistic missile interceptors can expand this partnership by using some of the same equipment. Both countries are concerned that Chinese, Russian or North Korean hypersonic weapons with extremely high flight speeds could overwhelm existing defense systems.

According to the news of the Nikkei newspaper, Japan began work on new, larger rocket engines designed to power a hypersonic interceptor. The system will be derived in part from the SM-3 ballistic missile interceptor, also a joint US-Japan project, and the ship-launched SM-3 equipped with the Aegis combat system. The new interceptor will be designed for local coverage, and the existing Patriot PAC-3 missile will provide local protection of point targets.

Hypersonic weapons, or weapons moving at speeds above Mach 5, have become popular in recent years due to their ability to bypass existing air and space defenses. Cruise missiles reach their targets by flying low, hugging the ground at subsonic speeds. Ballistic missiles travel at high speed along a ballistic trajectory, curve upwards sharply, and then fall to Earth at a high angle. While they are difficult to catch, there are defenses against both.

Hypersonic weapons are different. The most difficult hypersonic weapon to defend is the so-called “boost-glide” hypersonic weapon. Accelerator Glide Guns launch like ballistic missiles, but temporarily stall before entering low Earth orbit. Instead, the weapon drops downward, remaining in the atmosphere and gliding back to its targets at hypersonic speeds. This flight profile presents defenders with a unique challenge: flying higher and faster than conventional air defense systems can hit, but below the range of ballistic missile interceptors. On top of that, fast-sliding weapons can make sudden, high-speed turns, which can make it difficult for a defender to block them.

The high speed of the hypersonics combined with the crowded neighborhood of East Asia makes the job of the defense even more difficult. China, Russia and now North Korea – they all use – or are working on – hypersonic weapons. Tokyo, the capital of Japan, is only 1200 miles from Beijing, the capital of China, a distance the Mach 10’s hypersonic weapon can cover in just over 12 minutes. North Korea’s capital, Pyongyang, and Russia’s regional city, Khabarovsk, are halfway away; this leaves little time for defenders to stop the hypersonic weapon before it begins to take down their targets.

An archipelago of United States military bases in Asia equally vulnerable it would have faced hypersonic weapons and, in the event of an invasion of Taiwan, possibly attacked by Chinese forces. The People’s Liberation Army understands that any US military support to Taiwan will be provided through nearby bases such as Kadena Air Force Base on the island of Okinawa, Yokota Air Force Base on the outskirts of Tokyo, and Naval Base for Fleet Activities Sasebo near Nagasaki. . . Damage to these objects by a devastating blow, including hypersonic weapons, is almost a necessary condition for the successful Chinese invasion of the island.

As the war in Ukraine has shown, when a major conflict erupts, a military state will likely use every non-nuclear weapon in its arsenal, making defense against weapons like China’s DF-17 hypersonic weapon a top priority. Japan plans to install new hypersonic interceptors on its Aegis-equipped destroyers, including two new anti-missile defense ships scheduled to enter service in the late 2020s. The unnamed interceptor will be compatible with most, if not all, of the US Navy’s current destroyers and cruisers, meaning it can be deployed globally, not just in Asia.