Russia has reportedly conducted the longest range surface-to-air missile test ever with its S-500. If and when it becomes operational, the air and missile defence system could significantly increase the Russian military’s anti-access and area denial capabilities in Europe, East Asia, and elsewhere, but its already years behind schedule.

CNBC was first to report on the development, citing unnamed sources familiar with U.S. intelligence on the Russian program, but its story did not say when the launch occurred. According to the anonymous individuals, the S-500 was able to hit a target just shy of 300 miles away, which is some 50 miles further than the previous record. The stated range of the existing S-400 system when using the 40N6 missile is almost 250 miles.

Though the system, also known as the Triumfator-M or Prometheus, has been in active development since at least 2009, there are few firm details about its capabilities. Russian media has reported in the past that the final production S-500s will be able to engage opponents up to 370 miles away.

Depending on the exact missile type the launcher carries, it will supposedly be able to shoot-down both air-breathing targets, including manned aircraft, drones, and cruise missiles, as well as ballistic missiles. The latter capability appears to be the most immediately important to the Russians and many reports indicate that the road-mobile S-500 is likely to act primarily as a more flexible and survivable replacement, or at least supplement, for Russia’s fixed, silo-based A-135 anti-ballistic missile system.

The S-500s would otherwise supplement existing S-400 surface-to-air missile systems and provide theater ballistic missile defense and other long-range capabilities as necessary. The air and missile defense system would also compliment the still-in-development A-235 ballistic missile defense system, which is another road-mobile system that reportedly is actually primarily an anti-satellite weapon.

S-500s would be ideal for providing regional ballistic missile defense along Russia’s European borders with NATO. It is in many ways roughly analogous to the U.S.-made Terminal High Altitude Area Defense system, or THAAD, though the goal is clearly to offer flexibility to respond to more conventional aerial threats, as well. 

It is also possible that there could eventually be a naval version that would give future Russian warships a ballistic missile defense capability. Two of the new missiles for the S-500, the 77N6-N and 77N6-N1, will reportedly be capable of mid-course intercepts against ballistic missiles, with broad performance similar to the U.S. Navy’s Aegis Ballistic Missile Defense system using the SM-3 interceptor on some Arleigh Burke-class destroyers.

The Kremlin could see a significant new impetus for pushing ahead with the S-500 since the United States has been openly talking about the possibility of new nuclear-armed sea-launched cruise missiles, as well as new, long-range ground-based missile and rocket artillery systems. The U.S. military says these systems necessary to meet various emerging security concerns, but especially those coming from Russia as a result of its increasingly assertive foreign policy.

In addition, the Russian military might see S-500 as essential to defending its eastern flank, particularly against any potential Chinese intrusions. China is notably not limited by the provisions of the Intermediate-Range Nuclear Forces Treaty, or INF, which Russia is party to with the United States.

As such, China has developed a large array of medium and intermediate range ballistic missiles with both conventional and nuclear payloads, as well as special maneuverable variants that can engage moving naval targets. Of course, the United States has accused Russia of violating the INF itself with a nuclear-capable ground-launched cruise missile.

There are reports that the S-500 will be able to able to shoot down hypersonic missiles, but it is unclear whether or not this refers to ballistic missiles in their terminal phase of flight or missiles cruising at hypersonic velocities, such as boost-glide vehicles or air-breathing hypersonic cruise missiles. Missile manufacturer Almaz-Antey has also claimed the system will be able to shoot down stealth aircraft, such as the U.S. F-22 Raptor and F-35 Joint Strike Fighter – a claim that the Kremlin has made about the S-300 and S-400, too – but that capability would be reliant on the ability of the associated radars to detect and track low-observable targets.

The CNBC report does not say what radars or other sensors were used in the latest long-range test. At present, it is understood that the 91N6E(M) S-band acquisition radar, 96L6-TsP C-band acquisition radar, 76T6 multi-mode engagement radar, and 77T6 anti-ballistic missile engagement radar are all parts of the S-500 system, but it’s unclear if this is the full suite of associated systems or how they necessary function together.

With these sensors, Almaz-Antey says the complete S-500 system will be able to perform more traditional air defense functions at extreme ranges, as well. Reports have pointed to Russian interest in potentially being able to use the weapons to shoot down combat support aircraft, such as the American E-3 Sentry Airborne Warning and Control System (AWACS) aircraft, which are already facing the potential need to operate further and further from the front lines in the face of improving integrated air defenses.

All told, even if the versions of the S-500 that eventually enter service have more limited target engagement capabilities than Almaz-Antey has claimed so far, with a maximum range of nearly 300 miles, the system will still present a considerable threat in a traditional air defense role, especially when layered together with S-400s and other systems. Depending on the range and capabilities of the associated radars, if the Kremlin put the missiles in its Kaliningrad enclave, the range ring would cover the Baltic States of Estonia, Latvia, and Lithuania, as well as much of Poland, all of which are NATO members. Most of the Baltic Sea would be within range, too.

Place additional systems in Ukraine’s Crimea region, which Russia is illegally occupying, could present a significant challenge for forces operating in the Black Sea. And Russian forces in Syria could dramatically expand their air defense coverage with S-500s, as well, since the country is only about 450-miles long diagonally. From the Kremlin’s Syrian outpost at Khmeimim, SAM operators could have the range to hit targets as far away as northern Israel, Jordan, and western Iraq.

In Russia’s Far East, S-500 batteries could easily be within range of South Korea and Japan. Being able to challenge the latter country might be another important option for the Russians, who dispute control over portions of the Kuril Islands, which separate the Sea of Okhotsk from the North Pacific Ocean.

But while the reported S-500 long-range test would definitely be a significant milestone in the program, without knowing when it occurred, what parameters were, and whether it reflects other testing successes, it’s hard to say how close the system might be to becoming operational. As of 2016, the Russian military was reportedly considering purchasing at least five complete batteries and have them in service by 2020.

However, in 2009, Almaz-Antey had expected they could at least roll out the first models by 2012. By 2013, this had slipped to 2017 and the next year got pushed back to 2018. The Russian military has yet to announce it has taken delivery of any production S-500s.

The potential for foreign sales might help push the program along now, though. Just in the last 18 months, Almaz-Antey has seen an explosion of interest in the existing S-400 system and the increasing proliferation of ballistic missiles could make S-500 attractive to various countries. Even China, which is likely part of the reason why Russia development the system in the first place could be a customer. The country just received its first batch of S-400s in April 2018 and has a clear interest itself in anti-ballistic missile defense.

And with help from the Russian government in pitching it to allies and partners, the system could be a real competitor to other air and ballistic missile defense systems on the market. American defense contractors Raytheon and Lockheed Martin have also recently secured new sales of their Patriot PAC-3 Missile Segment Enhancement (MSE) and THAAD systems respectively.

Unfortunately, the Russian missile maker might find itself the victim of its own success. The plant that makes the S-400 will be churning out weapons to fulfil existing orders through at least 2025. It's unclear where Almaz-Antey plans to build the S-500s.

It seems hard to imagine that the company would not have accounted for the demands of future S-500 production, at least to some degree. Still, the surge in demand for the S-400 could have upended those projections.

Regardless, both the Russian government and Almaz-Antey remain committed to the program. If the reported test is any indication, the system's exact features and capabilities are likely to be of great interest to potential partners and opponents alike when it finally makes it debut.