White House National Security Council spokesman John Kirby said that US intelligence officials have information indicating that Russia now possesses this capability, but the weapon itself is not currently ready for use.

US officials are analyzing the information available to them about this emerging technology, and have conducted consultations with allies and partners on this issue.

"First, this is not an active capability and has not been deployed, and although Russia's pursuit of this particular capability is troubling, there is no direct threat to the safety of any individual," Kirby added.

He continued: "We are not talking about a weapon that can be used to attack humans or cause physical destruction here on Earth."

The White House confirmed its intelligence after a vague warning on Wednesday by House Intelligence Committee Chairman Mike Turner, Republican of Ohio, who urged the Biden administration to declassify information about what he called a “serious threat to national security.”