A submarine wreck discovered off the eastern coast of Sweden probably dates back to World War I rather than last year, which was first suspected, when Swedish military hunted for a suspected Russian submersible.

The ship's discovery last week by the Ocean X Team comes less than a year after Swedish troops and ships unsuccessfully hunted for a Russian submarine, reportedly cited near Stockholm, in the country's biggest military mobilization since the Cold War, according to Reuters.

The military said in a statement that the find was likely a Russian submarine that sank in 1916. It had collided with a Swedish ship in poor visibility, killing all 18 crew members.

The shipwreck hunters' company, Ocean X Team, had sent underwater footage of the wreck to the Swedish military. Cyrillic letters on the hull indicated it was Russian, reported Yahoo! News.

"I am 99.9 percent sure it's from 1916, but the next step is to go down again and confirm it," Dennis Asberg, a partner in Ocean X Team, told Reuters.

In response to this news, government-owned Russian news site Sputnik News launched a verbal attack on Sweden, saying "the paranoia has not ceased." "Here we go again..." said the scathing article, referring to last year's submarine hunt in the Stockholm archipelago, according to the Local.

Concerns about possible incursions by Russian submarines have increased as relations between Moscow and the West have worsened due to the Kremlin's support for pro-Russian separatists in Ukraine.

During the Cold War, the Swedish Navy repeatedly chased suspected Russian submarines along its east coast. Then, in a 1981 incident known as Whiskey on the Rocks, a Soviet nuclear Whiskey-class submarine was stranded far into Swedish waters after it ran aground, causing a diplomatic standoff.