Accidents happen. And Russia’s military looks to cover them up.

An August 8 accident at Russia’s Nonoksa missile testing facility left seven dead and caused a brief radiation spike in a nearby town. What went wrong?

Vague and potentially misleading statements by Russian authorities have only added to speculation that scientists were working on a nuclear propulsion system for one of the country’s more secretive weapons projects, possibly the Burevestnik nuclear-powered cruise missile. Here’s what you need to know:

1. Accidents happen frequently in the Russian military

Ever since the sinking of the Kursk submarine in 2000, the Russian military has had an image of being accident-prone. There have been at least six fires on Russian submarines since 2006 — and at least three explosions at ammunition storage depots since May. In July, a fire on the Losharik deep-sea submersible in July caused 14 deaths.

Repairs are a dangerous time for the Russian navy, not just with the fires on submarines in dry dock, but also with the accidental sinking of the PD-50 floating dock in 2018, which almost sank and indefinitely disabled the sole Russian aircraft carrier.

But the recent deadly accidents involving nuclear-powered platforms like the Losharik and the Burevestnik missile are particularly dangerous for both the health of Russians in the vicinity and the reputation of the Russian military.

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2. And the military looks to cover up the story

The Russian military’s initial reaction to bad accidents is to try to cover them up. Despite evidence from atmospheric monitoring devices in Severodvinsk, the Russian military initially denied that any radiation had been released during the explosion, telling nearby residents that everything was safe and to avoid panic.

It took two days for Rosatom, Russia’s nuclear agency, to explain the cause of the accident and to admit that the explosion resulted in radioactive contamination. There is still no clear explanation of what exploded — or what the military was testing.

A Rosatom statement suggested the explosion resulted from tests of an isotope power source in a liquid propulsion system, leading to speculation about the type of system being tested. Experts believe it could be a nuclear-powered engine intended for Russia’s new cruise missile, a novel radioisotope thermoelectric generator or an experimental reactor meant to power one of Russia’s new weapon systems. Rumors also spread among the local population, leading to a run on iodine supplies in area pharmacies.

3. Russia is a leader in nuclear energy use

It would be an understatement to say that Russia’s government and military is remarkably comfortable with nuclear power, especially given the country’s history. Russia’s nuclear industrial complex continues to invest in forms of mobile nuclear power — for instance, the Academic Lomonosov floating nuclear power station launched this year, with the goal of providing power for Russia’s remote regions.

Russia’s nuclear industry has built deployable undersea nuclear power stations and designed containerized nuclear reactors for road mobile systems. The industry continues to work on various forms of power from radioisotope thermoelectric generators (RTGs) — which historically have powered Soviet satellites, lighthouses, sonar buoys and the like. The latest nuclear weapons — like the Burevestnik missile — are also nuclear powered, leveraging advances in Russian reactor design and miniaturization.

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4. Why is Russia building these weapons?

When President Vladimir Putin displayed what have been dubbed his “wonder weapons” in March 2018, he was unveiling projects that had been many years in the design and development phase as part of Russia’s strategy for managing escalation in a conflict with the United States.

Military planners at Russia's General Staff headquarters have developed several tiered strategies for escalation management, believing in the coercive power of long range conventional weapons, nonstrategic nuclear weapons, and their strategic nuclear forces. Moscow also believes that the United States broke a fundamental agreement underpinning stability by walking away from the ABM Treaty in 2002. In Russia's view this treaty enshrined mutual vulnerability, and the decision to fund the more novel nuclear weapon projects is partly tied to the abrogation of the ABM Treaty.

None of these weapons are in any way game changers in terms of the strategic balance. Some weapons, like the Avangard HGV and the Poseidon nuclear-powered torpedo are intended to counter U.S. investments in missile defense by ensuring that the U.S. homeland remains vulnerable to Russian nuclear weapons. Others, such as the Burevestnik nuclear-powered cruise missile, seem to be designed primarily to deter an adversary from attacking by causing it to fear the potential consequences of Russia’s response.

5. Where are Russia’s wonder weapons now?

Russia’s Kinzhal air-launched ballistic missile has likely entered service with at least one squadron of Mig-31K modified fighters. Russia’s Ministry of Defense announced that Peresvet, the road mobile laser system, had officially entered service in December 2018. The weapon is likely intended as an antisatellite or antimissile defensive countermeasures system.

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A new heavy liquid-fueled inter-continental ballistic missile (ICBM), Sarmat, is reportedly somewhat delayed and not slated to enter serial production until 2021. The missile program is likely 2 to 3 years behind its development time table, with few updates since spring 2018.

Vladimir Putin announced a successful flight test of Avangard HGV in late December 2018. Pronouncements like this come with a degree of skepticism, given the incredible complexity of this type of technology. The hypersonic glide vehicle, a weapon that has the range and maneuverability of a regular cruise missile but flies at a much higher speed, will first be deployed aboard the SS-19 mod 3 Stiletto (UR-100UTTKh), until the heavier RS-28 Sarmat ICBM is complete.

Similarly, the Poseidon nuclear-powered strategic torpedo appears to be still in testing. In April 2019 Russia launched a new massive special-purpose submarine, known as project 09852 Belgorod, designed to carry Poseidon torpedoes and unmanned underwater vehicles, and serve as a mother ship to Russia's deep-water diving atomic stations.

Burevestnik, the nuclear-powered cruise missile, appeared to be in trouble — analysts report it failed most of its tests since 2017. The project has low feasibility given the number of technological innovations required to make it work. In light of the program’s problems, it seems quite likely Russian scientists were indeed working on a novel way to power the missile at the time of last week’s accident.