Mark Milley, the Chairman of the Joint Chiefs of Staff, said the tests were close to a “Sputnik” moment, referring to the Soviet satellite launch in 1957 that prompted the arms race during the Cold War.
Last week, the Financial Times reported that China had conducted two tests of a new hypersonic missile system. The missiles, fired from a rocket in low-earth orbit, are thought to be capable of evading US defence systems.
In an interview with Bloomberg TV, General Milley became the first high-level US military figure to acknowledge the tests, saying they represented a “very significant event”.
He said: “I don’t know if it’s quite a Sputnik moment, but I think it’s very close to that. It has all of our attention.
“As we go forward -- over the next 10, 20, 25 years -- there’s no question in my mind that the biggest geostrategic challenge to the United States is gonna be China.
“They’ve developed a military that’s really significant.”
The launch of the Sputnik satellite shocked the US government, who feared the Soviet Union’s rapid technological progress. It spurred then President John F Kennedy to set a goal of landing on the moon within a decade, which was completed in 1969.
Gen Milley said that Chinese military capabilities were “much greater” than the missile tests, adding: “They’re expanding rapidly in space, in cyber and then in the traditional domains of land, sea and air.
“China is very significant on our horizon.”
Zhao Lijian, Beijing’s foreign affairs spokesman, disputed the Financial Times’ report and claimed the test was “a spacecraft, not a missile”.
Later on Wednesday, Pentagon spokesman John Kirby said there was a “suite of issues with respect to China that concern us”. These would “inform in many ways our training and exercise regimen” as well as the spending priorities of the department, he added.
President Biden has said that the US and China are locked in “strategic competition” as Beijing attempts to expand its global influence.
The United States and Russia have both tested hypersonic weapons.