The missile launched in August and circled the globe before speeding towards its target, which it missed by about two-dozen miles according to three individuals briefed on the intelligence. Two of those individuals said the test showed how far China has progressed on hypersonic weaponry – farther that U.S. officials realized.
"We have now idea how they did this," one individual told The Financial Times.
Taylor Fravel, an expert on Chinese nuclear weapons and professor at MIT, said it would be "destabilizing" if China fully developed and deployed such a weapon.
"Hypersonic glide vehicles…fly at lower trajectories and can maneuver in flight, which makes them hard to track and destroy," Fravel said.
U.S. military officials in recent months have warned about China’s growing nuclear capabilities, particularly after the release of satellite imagery that showed it was building over 100 intercontinental missile silos. Two sources familiar with the recent test noted that the weapon could, in theory, fly via the South Pole instead of the more heavily monitored North Pole route.
During a Senate Armed Services Committee hearing in March, Admiral Philip Davidson, head of Indo-Pacific command, warned against an increasing "imbalance" in the region brought on by China’s rapid military advance.
"The military balance in the Indo-Pacific is becoming more unfavorable for the United States and our allies," Davidson said. "With this imbalance, we are accumulating risk that may embolden China to unilaterally change the status quo before our forces may be able to deliver an effective response."
China announced earlier this year that it will increase its defense budget by 6.8% in 2022.
One major concern is that China is not currently tied to any arms-control deals and has yet to properly engage in talks with the U.S.
The Pentagon did not comment on the specific test, but did acknowledge that China is a top priority.
"We have made clear our concerns about the military capabilities China continues to pursue, capabilities that only increase tensions in the region and beyond," John Kirby, a Pentagon spokesperson, told Fox News. "That is one reason why we hold China as our number one pacing challenge."
The Pentagon did not respond to a Fox News request for comment.
Fox News' Caitlin McFall contributed to this report.