A TD and Defence Forces veteran says neutrality does not protect countries, and in fact makes them targets.
Cathal Berry was speaking as Ireland looks set to increase its annual defence spending by at least €500m in the coming years.
That is a 50% increase on current levels.
Deputy Berry told Newstalk Breakfast this would be a good start.
"We're hugely vulnerable and hugely exposed. Currently Ireland spends about one-quarter of the EU average on defence.
"If this 500m comes on-stream, which now looks likely that it will, we will then only be spending half the EU average.
"So we'll be still be a significant outlier, but at least this is a half a step in the right direction".
But he warns that Ireland will have to defend itself in the event of any conflict.
"What we've learned over the last number of years is neutrality is absolutely no protection at all: in fact, neutrality makes you a target.
"If you look at what happened in Georgia in 2008, in Ukraine in 2014 and again now - and what's likely to happen in Moldova in the next few weeks - these are all neutral countries.
"Being neutral gives you no protection, being neutral makes you a target.
"And it's really up to us to recognise that we have to protect this neutrality, whatever it means to whatever people, and that we should be able to defend our sovereignty and our territorial integrity.
"No one is going to fight for us - what we've learned as well over the last number of years is that nobody's going to start World War III to protect Ireland.
"We have to be prepared to protect ourselves.
"The Americans or the British they may fight alongside us, but they won't fight for us".
'No means to monitor our own airspace'
And he says the under-investment in defence goes back to the foundation of the State.
"There's a 100-year gap to be made up on.
"First of all we have to hire an additional 2,000 people just to get us back to where they were 10 years ago.
"Ten years ago, the number of people in our Defence Forces was 10,500 - and now it's dropped to 8,500.
"So we very badly need to get an additional 2,000 people to firstly man our naval ships, secondly to staff our cyber defences - but also then to staff our intelligence service as well."
He says equipment is also needed, as we are the only EU state without a military-grade primary radar system.
"We're the only EU country, out of the entire 27, that have no means to monitor our own airspace - which is a very sad indictment on the country, really.
"Secondly we do need transport aircraft, to be able to transport Irish citizens that are in trouble overseas, or humanitarian aid or even our own troops around.
"And... we need new helicopters as well that should be able to fight forest fires, we should be able to transfer patients from one hospital to the other and we should be able to conduct mountain rescue operations".
"People number one, and then infrastructure and equipment number two".
He explains that while Ireland does have radar capabilities, these are limited.
"The secondary radar that's in Dublin Airport and Shannon Airport at the moment, they can only detect aircraft that have their transponders turned on.
"Once an aircraft flicks off its transponder, which is very easy for it to do, they can't be detected by our civilian secondary radar in Dublin or Shannon.
"So we need military-grade just like every other EU country, so that we do have visibility of what's happening in our own airspace".