The US successfully tested a hypersonic missile in mid-March but kept it quiet for two weeks to avoid escalating tensions with Russia as President Joe Biden was about to travel to Europe, according to a defense official familiar with the matter.
The Hypersonic Air-breathing Weapon Concept (HAWC) was launched from a B-52 bomber off the west coast, the official said, in the first successful test of the Lockheed Martin version of the system. A booster engine accelerated the missile to high speed, at which point the air-breathing scramjet engine ignited and propelled the missile at hypersonic speeds of Mach 5 and above.
The official offered scant details of the missile test, only noting the missile flew above 65,000 feet and for more than 300 miles. But even at the lower end of hypersonic range -- about 3,800 miles per hour -- a flight of 300 miles is less than 5 minutes.
The test came days after Russia says it used its own hypersonic missile during its invasion of Ukraine, claiming it targeted an ammunition warehouse in western Ukraine.
US officials downplayed the significance of the Russian use of their hypersonic Kinzhal missile. Defense Secretary Lloyd Austin said he did not view it as "some sort of game changer" after the Russians announced the missile launch. Days later, Pentagon press secretary John Kirby said it was "hard to know what exactly the justification" was for the launch, since it targeted a stationary storage facility.