A Russian submarine hovering just 12 miles off the coast of Cork was likely testing NATO reaction times, a security analyst has said.
Ireland had to seek assistance from the UK to "chase" off the vessel around six month ago.
It is reported the British Navy sent a helicopter to drop sonar technology into the water, before sending an anti-submarine boat.
Security Analyst Senator Tom Clonan told The Hard Shoulder it was likely for surveillance.
"A Russian submarine... was detected just due south of Cork Harbour on the 12 mile limit outside our territorial waters," he said.
"An interesting location, so obviously they were probing our capacity - well, not our capacity - the Russians know that we have no capacity to detect them.
"The Russians have been doing this with submarines [and] surface vessels for quite some time now to test NATO reaction times.
"They're sort of waving the flag and saying, 'This is your weak link here... here we are just 12 miles outside Cork Harbour, see how long it takes for you to find us and intercept us'.
"That's what it's all about I'd say".
'We're not neutral'
Senator Clonan said seeking assistance from the UK means Ireland is not neutral.
"If the Royal Navy are patrolling our maritime domain for us, and if the Royal Air Force are patrolling our airspace then we're not neutral," he said.
"It's actually worse than neutral: we're depending on the UK - which isn't a European Union member - to do that work for us.
"That really undermines our sovereignty and it undermines our neutrality".
'One of the largest coastlines'
Senator Clonan said while Ireland may not be a target for Russia, our lack of defences is being exploited by them.
"Everybody knows that, through no fault of their own - this isn't the fault of the Naval Service, the Air Corps or the Army - maybe because of the peace dividend after the Good Friday Agreement, there has been a lack of proper investment and pay and conditions for our Defence Forces," he said.
"We don't have primary radar and we don't have sonar capability with the Naval Service.
"We don't have a lot of ships at the moment, a lot of capital assets are tied up in Haulbowline.
"We've one of the largest coastlines in the European Union; the Russians know this [and] they're exploiting it.
"They're also very interested in our sub-sea cables, the fibre-optic cables that carry data and internet.
"Basically, we connect the European Union with the continental United States," he added.
The Hard Shoulder host Kieran Cuddihy said earlier the incident showed our defence weaknesses.
Taoiseach Leo Varadkar has previously reiterated that Ireland will not be joining any military alliance, such as NATO.
In 1999, Ireland joined NATO's Partnership for Peace (PfP) programme and the Euro-Atlantic Partnership Council: a multilateral forum for dialogue, which brings together allies and partner countries in the Euro-Atlantic area.
Ireland contributes to a variety of PfP activities in areas such as generic planning for peacekeeping and peace support, operational procedures, logistics and training.
The Defence Forces also operate a UN peacekeeping school, which offers courses that are open to NATO allies and partners.
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