The Yantar entered waters in the Irish Exclusive Economic Zone last year.
There are concerns a Russian spy ship could be heading for Irish waters.
The Yantar is currently off the coast of Scotland and it's understood to be gathering intelligence and mapping undersea cables.
It was monitored by an Irish naval vessel and patrol aircraft when it entered the Irish Exclusive Economic Zone last year.
Security analyst Mullingar's Declan Power says it highlights how weak Ireland's defence is.
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