Sharp increases in popular support for Finnish and Swedish membership of Nato, courtesy of Vladimir Putin's war on Ukraine, have made applications from both states, traditionally militarily non-aligned, likely within months. They will certainly be admitted by the organisation.
Russia has promised to "retaliate" against what it claims to see as a breach of those countries' treaty obligations to remain neutral, with cyberattacks and reinforcement of Russian missiles seen as most likely. Any such bullying should be strenuously countered by further sanctions from fellow European Union member states.
The debate in both countries about the benefits of an alliance based on collective mutual defence guarantees will certainly play into that emerging on neutrality in Ireland, although here the argument about Nato membership will certainly be complicated by the latter's nuclear deterrence strategy.
While Nato membership does not require states either to build their own nuclear deterrence or to host nuclear weapons on their territory, the organisation's core doctrine is built around them, sharing them, and the idea they have kept the peace in Europe for 80 years.
In 2017, Ireland, in line with its long-standing commitment to non-proliferation, signed up, with 50 other states including Austria and Malta in Europe, to the landmark UN Treaty on the Prohibition of Nuclear Weapons (TPNW).
Seen as a first step towards the total elimination of nuclear weapons, it provides undertakings not to develop, test, produce, acquire, possess, stockpile, use or threaten to use nuclear weapons The treaty also prohibits the deployment of nuclear arms on national territory and the provision of assistance to any state in the conduct of prohibited activities. It is clearly incompatible with Nato membership.
But Ukraine is a game-changer in European security. The real threat to fellow member-states leaves us all with no option but to look again at how we see our responsibilities to one another.