(CNN) Defense officials have revealed to CNN details about the hypersonic missile President Donald Trump has long touted as a "super duper" new military weapon -- part of a major effort to catch up to Russian and Chinese hypersonic weapons programs.
Pentagon officials acknowledged for the first time some of the capabilities of the hypersonic missile, which Trump has described as traveling 17 times the speed of sound.
A senior defense official has told CNN that Trump has taken a special interest in the missile, revealing that Trump's oft-cited "17 times" faster figure derives from a test of a "hypersonic glide body" over the Pacific in March, a test that the Pentagon officially described as "successful" while revealing little additional information.
"What he was referring to, really, was the recent flight test that we've performed in March where we flew 17 times the speed of sound," the senior defense official said.
But the American effort still lags years behind those of Moscow and Beijing's already fielded weapons systems, with a US missile unlikely to be fielded until 2023.
Hypersonic missiles are traditionally defined as missiles that travel at least five times the speed of sound, which is more than 3,800 miles per hour, and are considered highly maneuverable and capable of operating at varying altitudes.
Trump has touted the missile being developed by the Pentagon on at least three separate occasions, referring to it as "a super duper" missile capable of traveling 17 times faster than anything currently in the US missile arsenal.
"We have a -- I call it the 'super-duper missile.' And I heard the other night, 17 times faster than what they have right now," Trump said in May.
Given their tremendous speed and ability to maneuver in the atmosphere, hypersonic missiles are seen as particularly hard to defend against using conventional missile defense systems, which are designed to counter and intercept traditional ballistic missile threats, the trajectory of which are much more predictable than their hypersonic counterparts.
"Trying to defend against a hypersonic vehicle, that uncertainty in trajectory, becomes very difficult to deal with and defenses become very difficult because you've coupled very high speed with uncertainty in flight trajectory," a senior US defense official told CNN.
The senior defense official revealed that Trump's oft cited "17 times" faster figure derives from a test of a "hypersonic glide body" over the Pacific in March, a test that the Pentagon described as "successful."
"What he was referring to, really, was the recent flight test that we've performed in March where we flew 17 times the speed of sound," the senior defense official said.
The official said that Trump "does get briefed" on the details of the hypersonic weapons program, saying "he is aware of and supportive of the progress we're making."
"There's presidential level support and interest in what we're doing," the official said.
The US military is still several years away from fielding a hypersonic weapon, however, with a target date of 2023 at the earliest, while America's adversaries, Russia and China, claim they have already fielded such weapons.
Russia said it placed its nuclear capable hypersonic missile known as "the Avangard" on "combat duty" late last year.
The Russian military has also tested an air launched version of a hypersonic missile known as the Kinzhal and has said it could field it this year.
And China recently showcased its hypersonic weapon, the DF-17, during a recent military parade.
The US has acknowledged that it needs to catch-up to Moscow and Beijing and the Pentagon has requested billions for the weapon's development.
"I have full confidence that we'll catch up, and we're investing in hypersonics," Assistant Secretary of Defense for Strategy, Plans, and Capabilities Vic Mercado told CNN, saying that the Russian and Chinese capabilities were a major planning factor for the Pentagon.
The senior official told CNN that the reason the US fell behind China and Russia in the hypersonic arms race is that the US made a conscious decision to avoid adapting hypersonic technology to weapons until relatively recently, a change spurred on by Moscow and Beijing's embrace of the armaments.
For four or five decades, "the United States has been a world leader in hypersonic technology. But we've always shied away from making the decision to transition that technology to war fighting applications," the senior defense official said.
"What helped us make the decision is that, you know, hey, the adversaries have made that decision to develop their hypersonic systems, and that really creates a potential asymmetry in war-fighting capability that we just can't allow to stand if we want to make sure we maintain our military dominance," the official said.
The US hypersonic weapons program is primarily focused on two types of missiles, a "boost glide system" derived from a traditional ballistic missile and a hypersonic cruise missile.
The boost glide system, which was the system tested in March, places a maneuverable glide vehicle atop a ballistic missile, giving the missile much enhanced maneuverability at hypersonic speed.
The weapon is seen as having tremendous range, 1,000 miles or greater, but is more expensive and larger than the cruise missile variant.
The other kind of hypersonic missile the US is working on is a hypersonic cruise missile and is much more like a traditional cruise missile such as the Tomahawk missile, a weapon long used by the military to strike enemy targets.
The hypersonic missiles would travel up to ten times faster than the Tomahawk missile currently in the military's arsenal.
The senior defense official said a test of the cruise missile would take place later this year.
The official said both weapons could work in concert with one another, with the longer range boost glide missiles taking out an enemy's air defense systems, allowing US warplanes armed with hypersonic cruise missiles to fly in closer and strike a greater number of enemy targets.
One major difference between the planned US weapons and the Chinese and Russian variants is that the American missiles are not designed to be nuclear capable according to US officials.