Ireland will have to decide how far it wants to stretch its own neutrality.
That's according to former Finnish prime minister Alexander Stubb, after his country applied to join the North Atlantic Treaty Organisation (NATO).
It has applied to the military alliance, along with neighbour Sweden, in the face of Russia's invasion of Ukraine.
Finland also shares a large border with Russia.
Accession of the two Nordic countries to the alliance would see Ireland, Austria, Malta and Cyprus as the only remaining European Union states outside of NATO.
Mr Stubb told The Hard Shoulder neutrality as a concept is becoming more problematic.
"In today's world neutrality - it's an important concept, everyone does their own choice.
"But in my mind, it's very difficult to be neutral in a conflict like this".
However he believes Ireland would not be side-lined in any NATO expansion.
"I would say that this would probably strengthen the European pillar of NATO.
"And probably because of American engagement now in the transatlantic partnership, and in NATO, I think a lot of the focus on defence cooperation will be on the NATO side of things - and not many countries want to duplicate the systems.
"But does this mean that Cyprus, Malta, Austria and Ireland are side-lined: no, I don't think so.
"It's all about their own commitment and how far they want to stretch their, so-to-speak, own neutrality in the Irish case and in the Austrian case.
"So it's pretty much up to those countries."
'It's not going to go away'
And he says these discussions are here to stay.
"There will be of course some conversation about the future of defence in the European Union.
"And it's not going to go away - again, this is very much a decision for Ireland itself".
Earlier this week Jim Townsend, a former US deputy assistant secretary of defence (DASD) for European and NATO Policy, said the alliance has 'an open door'.
He told Newstalk: "So for those nations that are not in, it's a matter for those nations and the people of those nations to decide - and understand how joining the alliance might help them in terms of their own threat perception.
"How does it feel to be part of an alliance in terms of the insecurity they may feel in their region?
"Ireland would be different from Austria, be different from Switzerland.
"Nations have their own views of things - and so the alliance has an open door.
"When that nation feels like Sweden and Finland did, that the situation has gotten dangerous for them or they feel insecure and want to join the alliance, NATO has an open door and NATO will be there".