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.
원문출처 : https://www.cnn.com/2022/04/04/politics/us-hypersonic-missile-test/index.html
원문출처 : https://www.cnn.com/2022/04/04/politics/us-hypersonic-missile-test/index.html