Is Putin playing war games in Irish Sea... quite possibly
Not surprisingly Ardglass fishing boat captain Paul Murphy was rather shocked when his vessel started to be pulled backwards at 10 knots.
Four Scottish fishermen were killed 25 years ago when the Antares was dragged underwater after a Royal Navy submarine snagged its nets, so the crew of the Karen were justifiably worried that they were in great danger on Wednesday afternoon.
Luckily, Murphy and his crew were able to release their nets and set their vessel free but the incident highlights the dangers posed by submarines getting too close to fishing boats. The air of mystery about the incident has not been lifted by cryptic comments from the Ministry of Defence that it "does not comment on submarine operations".
But the ministry has since made off the record comments that it was not a Royal Navy or Nato submarine.
So who would have sent a submarine into the Irish Sea? The prime candidate must be the Russian Navy. With more than 50 Nato warships currently exercising off the west coast of Scotland, it would not be a surprise that the Russians have sent a submarine into the region to monitor what is going on and to try to pick up intelligence.
British and Nato marines are poised to carry out an amphibious landing at Luce Bay outside Stranraer so the channel between Scotland and Northern Ireland is fast becoming a focus for international naval activity.
On top of this, the deep channels leading out of the Firth of Clyde have long been of interest to Russian submarines trying to detect and then follow Britain's Trident nuclear missile firing submarines as they leave their base at Faslane, to the west of Glasgow.
During the Cold War, the number of submarines plying their trade around the west coast of Scotland meant incidents involving trawlers were more frequent. Since the Americans pulled their submarines from the Clyde in 1992, and the Royal Navy slimmed down its fleet, the number of incidents has decreased dramatically.
After the loss of the Antares, the Royal Navy also put in place protocols to keep its submarines further away from fishing grounds and it began issuing warnings about exercise areas.
When a Russian bomber flew up the English Channel in January, Vladimir Putin's ambassador was summoned to the Foreign Office. If a Russian submarine is identified as being behind this incident, then the ambassador may have to make use of his official limousine again.
- Tim Ripley is a defence analyst for IHS Jane's Defence Weekly magazine