The U.S. Air Force in May said its X-51A Waverider test vehicle accelerated to a speed of Mach 5.1, or about 3,800 miles per hour, during a fight over the Pacific Ocean.
Russian Deputy Prime Minister Dmitry Rogozin, who's in charge of the defense industry, said the Kremlin was working to keep up with the United States in terms of military technology, Russia's state-run news agency RIA Novosti reports.
"Both we and the Americans conduct researches about hypersonic technologies, or speed that is more than six times above the speed of sound. This is not a secret, but everything else is," he was quoted as telling Rossiya TV. "I can tell you that we are running neck and neck with the Americans as far as these technologies are concerned."
Russia and the United States committed to phasing out some aspects of their nuclear arsenals under the terms of an arms reduction treaty agreed to in the 1970s. Both sides are at odds, however, over missile defense advances in Eastern Europe.
Russian officials said last year hypersonic aircraft could enter military service during the 2020s.