Hypersonic weapons can reach least five times the speed of sound – 6,200 kilometres an hour.
China, Russia and the US are investing billions of dollars in developing the weapons.
These are often missiles but also gun-fired projectiles and winged “glide vehicles,” which are designed to hit targets hundreds or even thousands of kilometres away.
Their speed denies the enemy valuable response time and makes the weapons difficult to shoot down.
South Korea's Defence Ministry released a statement on Tuesday condemning the launch as “regrettable for happening at a time when political stability on the Korean peninsula is very critical.”
On Wednesday, North Korea said their Hwasong-8 missile test was successful, displaying “the guiding manoeuvrability and the gliding flight characteristics of the detached hypersonic gliding warhead".
The South Korean military later released a brief assessment of the missile's performance, claiming that the weapon was only half way to hypersonic at mach 2.5, or two and a half times the speed of sound (3,087 kilometres per hour).
North Korean ambassador to the UN Kim Song previously hinted that weapons development would continue as a “deterrent” to what he called, “the possible outbreak of a new war on the Korean Peninsula”.
“[War] is contained not because of the US’s mercy on the DPRK, it is because our state is growing a reliable deterrent that can control the hostile forces in an attempted military invasion,” he told the UN General Assembly on Tuesday, referring to the Democratic People’s Republic of Korea, the official name for North Korea.
Chang Young-keun, a missile specialist at the Korea Aerospace University, in Goyang, South Korea, said the North's test weapon was likely unsuccessful, citing the missile's reported mach 2.5 performance.
“The North's HGV technology is not comparable to those of the US, Russia or China and for now seems to aim for short-range that can target South Korea or Japan,” Mr Chang said.