Russia's mysterious 'Doomsday Radio' has sent out another ominous message, with many fearing the hostile nation has just revealed its next target after Ukraine.

The mysterious station, which has been active since the Cold War, released a burst of sounds, with a voice heard saying 'Latvia'.

The signal was sent out on Monday, with many on social media fearing that Russia could be planning an offensive in the neighboring country.

However, with Latvia being a member of NATO, any attack would trigger a response from all other members of the bloc, including the US, and potentially set off World War III.

The radio channel is called UVB-76, nicknamed 'The Buzzer' or 'Doomsday Radio.'

It's a Russian shortwave station that has been running since the 1970s, mostly playing a constant, eerie buzzing sound like a faulty appliance. It is not known who regularly listens to it.

However, experts have suggested that the station is tied to Russia's strategic military command, possibly for sending secret orders, since the frequency of these signals typically increases during crises, such as the war in Ukraine.

Monday's surprise broadcast featured six different messages throughout the day, including one that read 'NZHTI NZHTI 15854 LATVIA 5894 4167.'

Other bits of Monday's code included the words NANTOTYUK, LAST, BOLONSKIY, GALVANIZER, and DRAW.

Although 'nantotyuk' did not appear to be translatable into Russian or English, 'bolonskiy' is a real Russian word, meaning bolognese, the traditional Italian meat sauce.

Italy is also a NATO member and was one of the organization's 12 founding members.

Meanwhile, the word 'galvanizer' is an English term for a worker who coats iron or steel with other metals, such as zinc.

Historically, the former Soviet Union was nicknamed the 'Iron Curtain' by Winston Churchill in 1946 because it deliberately isolated Russia and its satellite countries from the West, like a giant wall of iron dropped across Europe.

However, the direct naming of Latvia in the cryptic message has created the most panic as tensions between Russia, Ukraine and NATO remain dangerously high.

If Russia were to attack Latvia, it would trigger NATO's Article 5, a promise that all members of the international alliance would defend each other, potentially leading to an all-out nuclear war.

Despite the nightmarish consequences of World War III breaking out in Europe, some Russian-speaking users on social media welcomed the possibility of the invasion.

'Can Latvia be erased from maps?? Has it started!!????' one person asked. 

'We should also add Estonia and Lithuania,' another social media user commented, translated from Russian.

As the poster noted, Latvia, Estonia and Lithuania are all smaller NATO countries that sit along the Russian border.

NATO members Norway, Finland, and Poland also share a border with Russia, which has threatened to retaliate if Ukraine were to be admitted to the alliance.

However, many fear Russia's war in Europe has already spread to bloc nations in secret, through the use of drones and sabotage.

On Monday, the same day as the Doomsday Radio transmission, Polish Prime Minister Donald Tusk hinted that he suspected Russia of a major train explosion over the weekend, calling it an 'unprecedented act of sabotage.'

Polish authorities have also detained dozens of people over suspected acts of sabotage and espionage since Russia's invasion of Ukraine began in February 2022.

Belgium, Estonia, the Czech Republic, and Denmark have spotted unidentified drones over military bases and airports in recent months, with these NATO members also suspecting they came from Russia.

The incursions led to airspace shutdowns, flight delays stranding thousands of passengers, and emergency NATO meetings.

'Putin's hybrid warfare has already hit Europe with drones, sabotage and cyber operations. Now he's rattling the nuclear-coded channels,' one person on X warned.