US officials confirmed to CNN that Russia launched hypersonic missiles against Ukraine last week, the first known use of such missiles in combat. The US was able to track the launches in real time, the sources said.

The launches were likely intended to test the weapons and send a message to the West about Russian capabilities, multiple sources suggest.

Russia’s Ministry of Defence said Saturday that it had launched hypersonic Kinzhal missiles against a military ammunitions warehouse in western Ukraine on Friday, destroying the structure in the Ukrainian village of Delyatin. KFS can not independently verify this claim. 

Traveling at Mach 5 speed or faster, hypersonic weapons are difficult to detect, posing a challenge to missile defense systems. Hypersonic missiles can travel at a far lower trajectory than high-arcing ballistic missiles, which can be easily detectable. Hypersonics can also maneuver and evade missile defense systems.

The Pentagon has made developing hypersonic weapons one of its top priorities, particularly as China and Russia are working to develop their own versions.