Russia conducted a successful flight test of a developmental anti-satellite missile on Wednesday that is capable of destroying satellites in orbit, American defense officials said.

The Nudol direct ascent anti-satellite missile was launched from the Plesetsk test launch facility, located 500 miles north of Moscow, said officials familiar with the situation.

The missile was monitored by U.S. intelligence satellites and the test appeared to be successful.

The launch marks another major milestone for Moscow’s efforts to develop weapons capable of destroying U.S. navigation, communications, and intelligence satellites, a key strategic advantage.

No additional details were available, and it could not be learned if the Nudol missile was fired against a satellite or was test launched in a suborbital trajectory without hitting a target.

It was the second successful test of the Nudol, following a Nov. 18 launch, and shows Russia is advancing its anti-satellite weaponry.

Pentagon spokeswoman Lt. Col. Michelle Baldanza declined to comment.

Under Russian President Vladimir Putin, Moscow is modernizing its entire strategic arsenal and developing new weapons like anti-satellite missiles.

Air Force Lt. Gen. David J. Buck, commander of the Joint Functional Component Command for Space, told a House hearing in March that the Russians are developing space weapons, known as "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 told the House Armed Services Strategic Forces Subcommittee.

Gen. John Hyten, the commander of Air Force Space Command, also has said both Russia and China are building space weapons. "They are developing capabilities that concern us," Hyten has said in press reports.

Russia’s Nudol program has been couched in secrecy, but it appears linked to Moscow’s missile defense systems. State-run press reports in the past have mentioned the Nudol experimental development project as a "a new Russian long-range missile defense and space defense intercept complex."

Former Pentagon official Mark Schneider said senior U.S. military leaders have been warning about Russian anti-satellite threats for years and regard it as serious.

"GPS guidance has been widely adopted for many of our weapons because it was cheap, all weather, and works well in low and medium intensity conventional conflict," he said. "The loss of GPS guidance due to [anti-satellite] attack would take out a substantial part of our precision weapons delivery capability and essentially all of our standoff capability."

Geneva-based Russian military analyst Pavel Podvig speculated whether Russia may have conducted a simulated intercept in the latest test.

How the Nudol program fits within Russia’s military doctrine is difficult to assess, he said.

"My take is that it is not necessarily part of a well thought out strategic plan," Podvig said.

Soviet-era and current Russian weapons developments were often developed without a clear idea on how they would be employed.

"I wouldn't be surprised if the [Nudol] system is being developed just because it can be developed—they will think about its role later, assuming that it works," he noted.

Podvig said the apparent missile manufacturer, Almaz-Antey, "is making an argument that an [anti-satellite] system might be useful to hold U.S. [low-earth orbit] assets at risk."

"But if it gets to a real conflict scenario it is very difficult to see how this capability might be militarily useful," he added.

A Defense Intelligence Agency report to Congress in February 2015 warned that, "Russia’s military doctrine emphasizes space defense as a vital component of its national defense. Russian leaders openly assert that the Russian armed forces have anti-satellite weapons and conduct anti-satellite research."

Schneider said the threat to U.S. satellites is compounded by a lack of kinetic U.S. counter-space capabilities that could hold Russian Glonass satellites at risk.

China also is developing anti-satellite missiles and in 2007 conducted a test of a missile that destroyed a weather satellite, resulting in tens of thousands of pieces of dangerous orbiting debris.

The blog Planet4589.org, which monitors space launches, lists three earlier Nudol tests, including an April 22, 2015, test that failed. The two other tests were the successful launch on Nov. 18 and an Aug. 12, 2014 launch.

The blog identified the Russian designation for the Nudol missile as "14Ts033."

Coincidentally, the Nudol test took place a day before the Air Force Space Command concluded a major annual war game involving a notional Russian adversary armed with both direct ascent anti-satellite missiles and orbiting anti-satellite robots, command officials told reporters.

Air Force Col. Mike Angle, Space Command’s chief of training, weapons, and tactics, said the exercise involved European allies and U.S. forces facing off against a "peer competitor" in 2026 that appeared to be Russia.

The annual exercise is called Schriever Wargame 2016 and was held this year at Maxwell Air Force Base, Montgomery, Ala.

The exercise included simulated activities by missiles, cyber attacks, and orbiting satellite-killing robots. Scenarios also included cyber attacks against GPS satellites that provided false data to military GPS receivers that are widely used for navigating precision-guided weapons.

"We’ve got to, and we feel we need to, prepare for a crisis or conflict that might extend in the space domain," Angle said.

Jason Altchek, a Space Command official who directed the war game, would not say if the notional adversary was Russia. "I can tell you it was a global scenario that focused on the European Command," he said, noting that the scenarios were split evenly among space and cyber crisis and conflict simulations and responses.

Pressed on whether Russia was the adversary, Altchek said such details remain classified. "But I can tell you that the Schriever Wargame has gone from looking at a near-peer competitor, to a peer competitor," he said.

The seven allied nations that took part in the war games were not immediately identified by the Air Force. However, Angle said one lesson was that "were not all on the same sheet of music" in dealing with space and cyber threats.

Past Air Force exercises had been limited to mainly launching and controlling satellites in a relatively peaceful space domain. "We had never trained to perform in the face of a thinking adversary," Angle said.

In recent years and including the recent war game, the military has begun training to deal with space threats such as "what happens when you have a direct ascent [missile] launched against a satellite," Angle said.

Missiles are easier to identify than unidentified, small maneuvering satellites that might either be a killer anti-satellite robot or a benign maintenance satellite.

The goal of the exercise was to simulate coalition warfare that extends into space and cyber space.

The scenarios took place in the European Command area and included "a full spectrum of threats across diverse operating environments to challenge civilian and military leaders, planners and space system operators, as well as the capabilities they employ."

About 200 military personnel and civilians from 27 commands and agencies took part.