There are thought to be several Russian warships in the Irish Sea, lingering around 100km off the coast of Cork.
While Russian navy ships cannot be tracked on public marine traffic radars, their support ships can.
The Irish Defence Forces told Cork Beo they are "monitoring the situation" after support ship Vjazma was spotted on Tuesday evening.
READ MORE: Suspected Russian 'spy ship' spotted loitering off coast of Ireland after 'going off track'
The Vjazma is an oil tanker ship for the Russian navy, travelling as a support ship and shadowing the giant fighting ships of the Northern Fleet - the branch of the Russian navy responsible for defence in the Arctic seas.
It's thought to be accompanied in the Irish sea by the cruiser Marshal Ustinov, the destroyer Vice Admiral Ustinov and an unnamed submarine.
The Vjazma drew the attention of security experts who track Russian naval activity after it was spotted 54 nautical miles (100km) away from the Old Head of Kinsale at 7am on Wednesday.
Defence analyst H. I. Sutton reported that the oiler is likely accompanying "heavily armed" warships that are approaching the UK via the Irish Sea.
He wrote on Twitter: "Russian warships approaching UK, seemingly for a controversial passage through British territorial waters, are making progress. Currently doing 10 knots, this may take a while."
He added that the Russian warships were understood to be returning home after more than six months deployed to the Mediterranean to support Russia’s illegal invasion of Ukraine.
Retired Dutch journalist Hans de Vreij also posted on Twitter: "A Russian naval squadron approaches the Irish Sea. These are the cruiser Marshal Ustinov, the destroyer Vice Admiral Ustinov, an unnamed submarine and the tanker Vjazma.
"Only the latter is 'visible' on tracking sites such as MarineTraffic."
They are being dramatically stalked by some of Britain's Royal Navy warships.
The HMS Lancaster from the British armed forces is shadowing the fleet in the Irish sea.
The recent Russian activity off the Irish coast comes after a naval support ship made a surprise appearance just two weeks ago.
Another oiler, the Akademik Pashin, popped up around 140kms from Cork and was suspected to also have been operating "along with an unknown companion."
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