WASHINGTON — The Air Force and the Defense Advanced Research Projects Agency quietly conducted a successful hypersonic missile test last month.

A defense official told Defense News the Pentagon chose not to announce the test of the Hypersonic Air-breathing Weapon Concept, or HAWC, for about two weeks to avoid inflaming already-delicate tensions with Russia.

The free-flight test involved the version of the HAWC created by Lockheed Martin and Aerojet Rocketdyne and was released from a B-52 Stratofortress off the West Coast in mid-March, the defense official said.

A DARPA release Tuesday said the HAWC missile was boosted until its air-breathing, Aerojet-made scramjet engine ignited and quickly accelerated to speeds faster than Mach 5. DARPA said it maintained that speed for an extended period of time, reached altitudes higher than 65,000 feet, and flew for more 300 nautical miles.

Details of the test and the reason it was not immediately announced were first reported by CNN.

The defense official said the HAWC test took place shortly after Russia said it used one of its own hypersonic weapons against Ukraine and was the same week as President Joe Biden’s trip to Europe, which began March 23.

He compared the Pentagon’s decision not to immediately reveal the test to its decision to postpone a Minuteman III intercontinental ballistic missile test in early March. That ICBM test was delayed after Russian President Vladimir Putin put his nation’s nuclear forces on higher alert, and the Pentagon said it wanted to avoid any possible misunderstanding over the Minuteman test.

Air Force Gen. Tod Wolters, head of U.S. European Command, confirmed in a Senate Armed Services Committee hearing last week Russia had launched several hypersonic weapons against targets in Ukraine.

DARPA said the March test marked the second successful flight for the HAWC, following a September 2021 test of Raytheon Technologies’ version of the missile.

Andrew Knoedler, the HAWC program manager in DARPA’s Tactical Technology Office, said the program is now analyzing data from the flight test.

“This Lockheed Martin HAWC flight test successfully demonstrated a second design that will allow our warfighters to competitively select the right capabilities to dominate the battlefield,” Knoedler said. “These achievements increase the level of technical maturity for transitioning HAWC to a service program of record.”

Hypersonic weapons can travel at tremendous speeds, more than five times the speed of sound, and are highly maneuverable. Because they are able to change course midflight, they are much harder to track and shoot down than conventional ballistic missiles, making them capable of penetrating enemy defenses.

The successful test gives Air Force hypersonics a win after a string of setbacks. The Air Force’s main hypersonic program, the AGM-183A Air-Launched Rapid Response Weapon, or ARRW, saw testing failures and delays in 2021 that prompted Congress to strike nearly $161 million in procurement funds in the 2022 spending bill and divert half of that amount to research and development. The Air Force’s proposed fiscal 2023 budget seeks to increase funding for hypersonic prototyping, but doesn’t call for any procurement funds next year.

Stephen Losey is the air warfare reporter for Defense News. He previously covered leadership and personnel issues at Air Force Times, and the Pentagon, special operations and air warfare at Military.com. He has traveled to the Middle East to cover U.S. Air Force operations.

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