A security analyst believes the Russian vessels seen in Irish waters in recent days were likely monitoring under-sea cables, connecting the US and Europe.
The Defence Forces have confirmed four vessels were spotted off the south coast.
The Russian ships were monitored by Irish air and naval patrols, and have since departed the area.
Defence expert Declan Power explains the significance of the undersea cables in the area.
"They are responsible for a huge amount of commercial and other traffic between the United States and Europe.
"Damage to them would damage internet traffic of a personal nature, of a national nature, of an international nature.
"The other aspect of this is that it is known since the war in Ukraine that the Russians have been targeting and mapping under-sea cables, wind farms, anything of that nature."
