Russia successfully flight tested a new missile capable of knocking out strategic U.S. communications and navigation satellites, according to Pentagon officials.

The test of the PL-19 Nudol missile was carried out Dec. 16 from a base in central Russia, and was monitored by U.S. intelligence agencies.

It was the fifth test of the Nudol missile and the third successful flight of a system Moscow has claimed is for use against enemy missiles, said officials familiar with the reports of the launch.

The exact location of the flight test was not disclosed. Earlier tests of the missile took place from a facility near Plesetsk, located 500 miles north of Moscow.

It could not be learned if the Nudol was sent into space or fired in a sub-orbital trajectory.

Pentagon spokeswoman Lt. Col. Michelle Baldanza declined to comment. "We generally don't comment on other countries' capabilities," she said.

Earlier tests took place May 24 and Nov. 18, 2015. Both tests were first reported by the Washington Free Beacon.

The high rate of testing is an indication the program is a military priority and is progressing toward deployment.

The new anti-satellite missile is among several new strategic weapons systems being developed by the Russian military.

The Nudol is viewed by the Pentagon as a so-called "direct ascent" anti-satellite missile. Russia, however, has sought to mask the missile's anti-satellite capabilities by claiming the missile is for defense against incoming ballistic missiles.

The Pentagon is worried about the development of anti-satellite weapons by both Russia and China.

Gen. John Hyten, the commander of Air Force Space Command who was recently promoted to lead Strategic Command, has stated that Russia and China are building space warfare systems that are worrying. "They are developing capabilities that concern us," Hyten has said.

In March, Air Force Lt. Gen. David J. Buck, commander of the Joint Functional Component Command for Space, revealed during House testimony that the Russian military is developing weapons with "counter-space capabilities."

"Russia views U.S. dependency on space as an exploitable vulnerability, and they are taking deliberate actions to strengthen their counter-space capabilities," Buck said.

Mark Schneider, a former Pentagon strategic arms policymaker, said the current asymmetry between the United States and other nations in anti-satellite capabilities "is of enormous significance."

"Potentially, it could result in our defeat in a high intensity conflict," Schneider said. "The complete loss of the GPS network, or its serious degradation, would eliminate the effectiveness of all existing long-range conventional strike cruise missiles and would degrade the functioning of many of our precision guided weapons."

Anti-satellite missiles also could be used to knock out communications satellites. "We have begun to take some steps to reduce our reliance on GPS but this will not be near term," Schneider said.

Michaela Dodge, a defense analyst at the Heritage Foundation, said the Russian test highlights the growing threat to space from new weapons.

"The test demonstrates the need for the United States to treat space as an increasingly contested environment where access might not be guaranteed as it has been in the past," she said.

"It demonstrates the need to exercise scenarios in which U.S. military might not have a complete access to its complete utilization," Dodge added. "The test also illustrates the need to protect and diversify U.S. space infrastructure."

U.S. intelligence agencies have estimated that U.S. military operations could be severely disrupted with only two dozen or so anti-satellite attacks.

Satellites are used for precision navigation, targeting, and communications and intelligence gathering.

The Pentagon is very dependent on satellites for long-range warfare operations, an American military specialty.

Both Russia and China have recognized the strategic vulnerability of U.S. dependency on satellites. Anti-satellite missiles are regarded as important asymmetric warfare weapons.

Both China and Russia are developing lasers and other directed-energy weapons that can blind or disrupt satellites. Small satellites capable of maneuvering in space and grabbing and crushing satellites also are being developed.

Russian generals have mentioned their forces fielding anti-satellite capabilities in public statements, but with few details. For example, Russian Lt. Gen. Oleg Ostapenko, former commander of space forces, has said the S-500 anti-missile system is capable of hitting "low-orbit satellites and space weapons."

In May, Vadim Kozyulin, a professor at the Academy of Military Sciences, was quoted as saying that discussion of "space kamikazes" suggests Moscow is preparing for a conflict in space with the United States.

The TASS news agency reported that the A-60, a variation of the IL-76 transport aircraft, has a laser anti-satellite capability.

In October, TASS reported that the Nudol is called the A-235 and is being developed to replace the current nuclear-tipped missile defense system ringing Moscow.

Missile defense interceptors share characteristics with space-faring satellite killers. Both travel at high rates of speed and require precision targeting and guidance.

The United States has no anti-satellite weapons. However, a Navy SM-3 anti-missile interceptor was modified to shoot down a de-orbiting intelligence satellite in 2008, indicating U.S. missile defenses could be used to target foreign satellites.

The Defense Intelligence Agency stated in a report to Congress last year that Russia leaders "openly assert that the Russian armed forces have anti-satellite weapons and conduct anti-satellite research."

China conducted a flight test of its new anti-satellite missile in early December. Preparations for the test were first reported by the Free Beacon.

The missile was identified as a DN-3 direct ascent missile. That system, like the Russian Nudol, is being developed under cover as a missile-defense weapon.

China's Defense Ministry said the Free Beacon report of test preparations for the DN-3 was "groundless."