The United States announced Friday it has successfully tested an unarmed prototype of a hypersonic missile, a weapon that could potentially overwhelm an adversary's defense systems.
The Pentagon said a test missile flew at hypersonic speeds - more than five times the speed of sound, or Mach 5 - to a designated impact point.
The test followed the first joint US Army and Navy flight experiment in October 2017, when the prototype missile demonstrated it could glide in the direction of a target at hypersonic speed.
"Today we validated our design and are now ready to move to the next phase towards fielding a hypersonic strike capability," Vice Admiral Johnny Wolfe said in a statement.
Hypersonic weapons can take missile warfare, particularly nuclear warfare, to a new - and, for many, frightening - level.
They can travel much faster than current nuclear-capable ballistic and cruise missiles at very low altitude, can switch direction in flight and do not follow a predictable arc like conventional missiles, making them much harder to track and intercept.
Even as conventionally armed, non-nuclear weapons, they are viewed by analysts as raising the danger of conflict, because an adversary might not know how they are armed when launched.
The Pentagon is pressing to catch up with rivals Moscow and Beijing in the race to develop hypersonics, even as it recognizes they could dangerously raise the risks of a nuclear conflict.
In its fiscal 2021 budget the US Defense Department requested $3.2 billion for hypersonic programs, up from over $2 billion in the current year. According to reports, the goal is a deployable hypersonic capability by 2023.
In December, Russia declared it had placed into service its first Avangard hypersonic missile, making it the first country to claim an operable hypersonic weapon.
Russian officials claimed that in tests it had reached speeds of up to Mach 27, roughly 33,000 kilometers (20,500 miles) per hour.
China is also investing significantly in their development. Last October it displayed its DF-17 hypersonic glide vehicle in its national day military parade.
The US military is meanwhile pouring money into advanced missile defense research to find ways to protect against hypersonics. A senior NATO official warned that in a hypersonic missile strike, it may not even be clear what the target is "until there's a boom on the ground".
In January the Bulletin of Atomic Scientists advanced its "Doomsday Clock," its assessment of the risk of nuclear holocaust, in part due to the rising threat of hypersonic weapons.
"There is increasing investment in and deployment of hypersonic weapons that will severely limit response times available to targeted nations and create a dangerous degree of ambiguity and uncertainty," it said.
"This uncertainty could lead to rapid escalation of military conflicts. At a minimum, these weapons are highly destabilizing and presage a new arms race."