The secretive 12th main directorate of the Russian defence ministry is tasked with safeguarding and managing Moscow's nuclear arsenal
Details of how Russia manages its nuclear weapons have remained shrouded in secrecy for decades, as has the elite military unit entrusted with overseeing the nation’s nuclear arsenal.
Information about the Russian Defence Ministry’s 12th Main Directorate, abbreviated in Russian as GUMO, has been tightly guarded, yet some aspects of the operations of this secretive division have been documented.
The 12th GUMO has been handling the country’s nuclear arsenal since Soviet times, providing protection, maintenance, and transportation.
It is responsible for securing all nuclear warhead storage facilities, including strategic airfields, laboratories, and maintenance bases. The 12th GUMO is also trained to prevent potential attacks and respond to nuclear accidents.
“They take their responsibilities quite seriously,” said Pavel Podvig, senior researcher at the UN Institute for Disarmament Research (UNIDIR) in Geneva.
“They guard those storage facilities, they perform maintenance as necessary, there’s a protection force against sabotage,” Podvig said. “And they would be responsible for delivering weapons to delivery systems.”
MOSCOW, RUSSIA - JUNE 24: (RUSSIA OUT) Russian nuclear missile rolls along Red Square during the military parade marking the 75th anniversary of Nazi defeat, on June 24, 2020 in Moscow, Russia. The requirement to wear masks and gloves to combat a spread of the Coronavirus (COVID-19) is still in effect in Moscow. (Photo by Mikhail Svetlov/Getty Images)
A Russian nuclear missile during a parade in Moscow’s Red Square (Photo: Mikhail Svetlov/Getty Images)
“Back in the Soviet days, they had this nickname, ‘deaf and dumb’, because they were literally prohibited from talking to other military units,” Podvig said.
The 12th GUMO personnel serve separately from the regular military, he said.
What happens when nuclear weapons are put on higher state of readiness?
Russia’s massive stockpile of nuclear warheads is stored at storage facilities across the country, which include about a dozen large national-level storage sites and additional base-level storage facilities, according to a 2023 UNIDIR report authored by Podvig.
Russia has the largest confirmed stockpile of nuclear warheads in the world, with more than 5,500 nuclear warheads, of which 1,710 are “deployed” – or ready for use – and supported by various strategic delivery systems.
All nuclear weapons that are not mated to their delivery systems are handled by the 12th Main Directorate, UNIDIR says.
The standard weapons deployment procedure involves several steps, which vary depending on the type of weapon. Weapons are usually stored separately from their delivery vehicles, according to UNIDIR.
“If the weapons in question are warheads of ballistic or cruise missiles, each of them is stored in a specialised container, only to be mated with the missile as part of the deployment procedure,” reads the report.
Gravity bombs, also known as unguided bombs, are stored in their containers assembled.
“Once the units receive an order to bring nuclear delivery systems to a higher state of readiness, the 12th GUMO units must take the weapons, still in containers, out of storage and load them onto specialised trucks,” the report reads.
“When this procedure is completed, the trucks deliver the containers to a designated point, where weapons are removed from the containers so that they can be mated with their delivery systems.”
For air-delivered weapons, such as bombs or air-launched cruise missiles, this step typically takes place at a designated area of an airbase where 12th GUMO personnel would perform the final assembly and prepare the weapon to be loaded onto the delivery aircraft.
“Fully assembled weapons at the airbase remain in the custody of the 12th GUMO troops until the very moment they are loaded onto an aircraft that is ready to take off, at which point custody is transferred to the flight crew,” according to UNIDIR.
Warheads of land-based ballistic and cruise missiles would be delivered to an initial assembly point away from a base, and mated with missiles and loaded on launchers in the field.
“It appears that the 12th GUMO troops can keep nuclear weapons outside of the storage facility for some time, probably days and maybe even weeks,” the report states. “However, at some point the weapons must be returned to the base-level facility that provides conditions for long-term storage.”
Russia’s nuclear weapon storage sites are spread across the vast country, according to research by Russianforces.org
Dmitry Kornev, a Russian military expert and columnist, has stated that if a nuclear storage facility were captured, it would be extremely difficult to detonate the warheads stored there, as they are protected by advanced coded security devices, according to state media.
Where does the 12th Main Directorate operate?
In addition to working at storage sites and base facilities across the mainland, 12th GUMO personnel also handle operations at the Novaya Zemlya archipelago in northern Russia – the country’s designated site for nuclear tests.
Russia says it has not conducted a nuclear test since 1990, the year before the Soviet Union dissolved.
The last nuclear test was conducted at the Novaya Zemlya test site on 24 October, 1990, according to Russian state news agency Tass. The Soviet Union had conducted more than 700 nuclear tests prior to that, according to Tass.
Russia’s deputy foreign minister Sergei Ryabkov reiterated in 2024 that “we can conduct such tests, but we will not hold any, given the United States refrains from such steps regarding [nuclear] tests”.
Ryabkov was clarifying comments by the head of the Novaya Zemlya test site, Rear Admiral Andrey Sinitsyn, who reportedly said nuclear tests can be conducted there “at any moment”.
“Nothing [regarding Russia’s nuclear tests] has changed,” Ryabkov said.
As Vladimir Putin announced in 2023 that Russia will store some of its nuclear weapons in neighbouring Belarus, 12th GUMO teams were likely involved in the transfer, analysts believe.
In this image made from video released by the Russian Presidential Press Service, on Wednesday, March 12, 2025, Russian President Vladimir Putin, right, accompanied by Russian Chief of General Staff Gen. Valery Gerasimov, second left, visits military headquarters in the Kursk region of Russia. (Russian Presidential Press Service via AP)
Russian President Vladimir Putin, accompanied by Chief of General Staff Gen. Valery Gerasimov, visits military headquarters in the Kursk region of Russia (Photo: Russian Presidential Press Service via AP)
The 12th main directorate also presumably handled the transfer of Russian missiles to Cuba in October 1962 during the Cuban Missile Crisis, which analysts believe was a close call to nuclear war with the US.
Operating in high secrecy
The 12th Main Directorate personnel operate in high secrecy and are reportedly forbidden from sharing details of their work with anyone outside their units.
“There is a very strict selection process there. Everyone is a professional soldier – no conscripts,” a deserter from the unit told the BBC last year. “There are constant checks and lie-detector tests for everyone.”
The officer said training exercises were being conducted regularly and soldiers were not allowed to bring any phones to the nuclear bases. “Our reaction time was two minutes.”
“It’s a closed society, there are no strangers there,” he said.