Cryptic messages have been broadcast on what has been dubbed "doomsday radio", a shortwave station in Russia that has been active since the Cold War.

The mysterious radio station UVB-76, thought to be linked to Russia's military, has been broadcasting since the 1970s on 4625 kHz and is occasionally interrupted by voice transmissions which prompt speculation about their meaning.

The white noise came to life again on Monday when cryptic voice messages of numbers and letters were heard, sparking a lively discussion on social media.

Why It Matters

Active for five decades, UVB-76 is widely believed to be a numbers station operated by the Russian military although this has not been confirmed.

Theories abound ranging from its role as a "doomsday station" which can trigger nuclear launches

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