Putin thought Ukraine war was a missile to Nato. It may be a boomerang

It is not yet a done deal. Opinion so volatile, and previously so settled in its opposition to Nato membership, could swing back towards the comforts of semi-neutrality. Russian nuclear threats, already starting, may intimidate voters into having second thoughts.

The process may be fraught. Many brands of Nato membership exist, and have yet to be fully explored by the Finns and the Swedes.

By invading Ukraine, Putin thought he had hurled a missile at the west. It has emerged to be a precision-guided boomerang. To have turned two stolidly non-aligned countries into Nato members would join the pantheon of great strategic blunders of wartime.

It is vital for the ruling Social Democrats, now launching an internal policy review, to be seen to be in charge of its own destiny. After all, last November the party had clearly affirmed its position that it opposed a foreign policy of alliances. Yet four centre-right parties now support Nato membership and two parties to the left are opposed to membership, claiming joining Nato implies coming to the defence of the authoritarians running Turkey and Hungary. With parliamentary elections looming in September, the SDP will want the review completed without the party descending into left-right splits.

But if Finland, or indeed Sweden, did set a mass of limiting preconditions concerning nuclear weapons, permanent bases or forces, the application process might be extended.

So there is an incentive to speed the application without delegitimising the domestic consultation.

For those who fear Nato escalating the conflict inside Ukraine, a sudden extension of article 5 obligations in the north remains alarming, and may make Putin even more convinced he was right to confront a Nato policy of encirclement. But for all its talk of red lines and the stationing of nuclear weapons, can Russia really open a second front to the north when the primary front to its south-west is proving so costly in lost lives, reputation and treasure?