While the main players in the Cold War were the United States and the Soviet Union, many European nations were also part of the struggle. Some, however, have maintained a certain degree of neutrality throughout the decades-long conflict and beyond — a neutrality which, in many cases, came from a show of force. Sweden was one of those neutral nations, and it was willing to go to war to protect that status. One of the most stark examples of this began in 1981, when a Soviet sub surfaced just a few miles off the coast of a major Swedish naval base. The event almost led to a battle between the two nations just days later, and sparked off more than a decade of distrust.

The relationship got so bad that one point, even the herring got involved.

Let’s start with the submarine. On October 27, 1981, the Swedish navy was running some test exercises well within their territorial waters. Unexpectedly, something ran aground, and even more unexpectedly, that “something” wasn’t a Swedish ship. It was a Whiskey-class Soviet sub, likely carrying nuclear warheads, and it most definitely should not have been where it was. (The incident became known as “Whiskey on the rocks” in the U.S., showing that a good pun is welcome even during times of conflict.) The Swedish military interrogated the ship’s captain, who claimed that the sub had simply gotten lost — which is unlikely, given how difficult it would have been to navigate that far into Swedish waters without functioning navigational equipment.

The Soviet government sent a rescue party to retrieve the sub but the Swedes were apparently willing to protect their territorial rights by force, leading to a standstill. Things almost blew up, both literally and figuratively, when two ships from the location of that rescue group broke off from the pack and headed into Swedish water. The Swedish navy’s scout team was able to identify the ships as German cargo haulers, averting war. The Swedish government ultimately returned the sub, but one could see how little the Swedes trusted the Soviets regardless.

This distrust lasted longer than the Soviet Union itself. The Swedish military installed submarine listening posts throughout their coastal regions and, in 1994 — a few years after the fall of the USSR — Sweden heard a series of loud clicking noises which sounded a lot like a Russian submarine. The sounds came from an area just outside of Stockholm Harbor, a part of Baltic Sea clearly within Sweden’s territorial waters. The Swedish Prime Minister at the time, Carl Bildt, was incensed by the Russian infraction. But he took a more peaceful approach than his Cold War predecessor; instead of scrambling the military, he wrote a nasty letter to then-Russian Prime Minister Boris Yeltsen.

Yeltsen probably claimed ignorance, for two reasons: (1) that seems diplomatically prudent and (2) as it turns out, it was the truth. There were no Russian subs in the region. A few years later, a team of Scottish researchers figured out the cause of the noise: the aforementioned herring.

Herring, apparently, have very good hearing. When herring gather in large groups at night, the researchers found that the fish speak to each other — but not through their mouths. Per National Geographic, the “high frequency sound bursts” emitted by the herring are “always accompanied by a fine stream of bubbles” coming from the fishes’ backsides. The researchers termed this “Fast Repetitive Tick,” or, FRT. The sound from below wasn’t a submarine. It was fish farts.

The Swedes did not declare war on the flatulent herring.

Bonus Fact : Google has a tool called Google Correlate which tells you if search traffic for a term has any other terms with similar search traffic patterns. Most of the correlations are coincidental, of course. One such correlation that is probably unrelated? The term “excessive flatulence” correlates highly with the term “free science fair projects” — that’s probably a coincidence, unless a lot of high schoolers used the former to inspire the latter.

From the Archives: Sounds from the Deep: The Bloop and Slow Down.

Related: Swedish fish.