Submariners patrolling the oceans may be among the last group of people on Earth to be blissfully unaware of how the coronavirus pandemic has turned the world upside down.

As part of their mission of nuclear deterrence, submariners are usually spared bad news to keep them focussed and avoid damaging morale.

The Associated Press reports that those crews that left port before the virus spread across the world are likely to be kept in the dark about the global crisis until they return to land.

“They won’t know,” said retired Admiral Dominique Salles, who commanded the French ballistic submarine squadron from 2003-2006. “The boys need to be completely available for their mission.”

Speaking exclusively to The Associated Press, Admiral Salles said he believes submariners will likely only be told of the pandemic as they head back to port, in the final two days of their mission.

“Those who are at sea don’t need this information,” said Mr Salles, who also commanded the nuclear-armed French submarine L’Inflexible.

“The commander, I think, is doubtless informed about what is happening. I don’t think he’ll have all the details,” he said.

The only news available to the crew is via messages to the commander of the submarine, who filters messages and will not provide everyone with all the information received.

The movements of nuclear submarines are closely guarded secrets, so the French navy won’t confirm if any submarines left port before France instituted a national lockdown on 17 March.

“Because the deterrent is wrapped in a bubble of protection and confidentiality, it is impossible to know whether the crews are informed or not of this situation,” French navy spokesman Lieutenant Commander Olivier Ribard said.

French submarine missions tend to last 60 to 70 days. A crew currently at sea may have no idea of the extent of the impact of the virus on their home country.

On 1 March, France had just 130 confirmed coronavirus cases and two deaths. In under a month, those numbers have surged past 2,600 dead and over 40,000 sickened. A crew returning to port will be in for a shock when they reach home. It could be worse for crews setting out who will be leaving family in the midst of a crisis.

Admiral Salles said he believes those crews will get regular coronavirus updates, but won’t be told of any family deaths.

“No matter how serious an event is, there is nothing a submariner can do about it. And since he cannot do anything, better that he know nothing,” Salles said. “They know that they won’t know and accept it. It’s part of our deal.”

France has four ballistic submarines, each with a crew of 110 and 16 missiles that can carry six nuclear warheads.

With reporting by The Associated Press