Concerns have been raised over the Russian Navy's plans to conduct military exercises 240km off the Cork coast next month.
The artillery drills, which are due to start in February, will be held in international waters but will remain in Irish controlled airspace and Ireland's exclusive economic zone (EEZ).
Fears have now been sparked of an internet outage and spying if the Russians access undersea cables located off the coast.
Irish Defence Forces Reservist Robert Gilbey has said the Russians identified the area as "ideal for protecting a submarine".
The news comes as Russia appears to be setting up to invade Ukraine as tensions grow along the Russia-Ukraine border.
But Mr Gibley also warned that this is not the first time a Russian operation near the British Isles has sparked panic.
However, this is not the first time a Russian operation off the coast has caused concern, as in 2017 and during summer 2021, a Russian spy ship was spotted.
The Russian Yantar vessel was spotted just north of Mayo and Donegal and appeared to be positioned near a commercial sub-sea cable.
The cables carry vast volumes of Internet traffic between Europe and the US.
Companies such as Facebook, Twitter, Amazon and Google rely on the cables to transmit vast amounts of data from Irish servers worldwide. If Russia cut these cables, the internet could go out.
The Yantar vessel was reportedly loaded with manned and remote-operated submersibles used to attach listening devices to the undersea cables.
Minister for Foreign Affairs, Simon Coveney has raised concerns about the Kremlin's exercises to Russia's ambassador to Ireland, Yury Filatov.
He said: "Under international law, including the UN Convention on the Law of the Sea (UNCLOS), states are entitled to carry out naval exercises in another state's EEZ.
"The Irish Aviation Authority (IAA) was informed of the exercise via standard procedures and has issued a statement to that effect.
"In light of the current political and security environment in Europe, the Department of Foreign Affairs has raised a number of concerns with the Russian authorities in respect of these exercises. We will continue these discussions in the coming days."
The underwater cables are not, in fact, the legal responsibility of the Irish navy service as they are legally the gardai's responsibility, under the 2004 Maritime Security Act, a role they are not believed to be capable of fulfilling.
John Brady, Sinn Fein's spokesman on defence, said: "There are vessels entering Ireland's exclusive economic zone which we don't have the ability to monitor.
"We have no idea what is happening below the surface. We don't know if devices are being fitted to these data cables or if they are being interfered with."
Mr Coveney pointed out the similarities of the exercise ship to the spy ship sighted off the coast.
He said: "What's interesting is that this exercise box is 170 nautical miles off the south coast of Ireland.
"Incidentally, so was a suspicious Russian trawler suspected of deploying submersibles back in July 2021, 170nm away. Could that previous event have been sub-surface reconnaissance?
"Others may recall that the Russians flew their ASW TU-142 Bears over that location in March 2020 too. Perhaps that was a subsurface signal mapping exercise? Testing reactions, or lack thereof?"
