NATO is committed to the principle of collective defence: that’s to say, “to the principle that an attack against one or several members is considered as an attack against all”.  It is written into Article Five of the Washington Treaty, under which NATO was set up.  The commitment is more than an agreement on paper.  It was invoked after 9/11 – which is why NATO is in Afghanistan.  It is therefore sobering to grasp that were Ukraine joined NATO, we would be today be contemplating the possibility of going to war with Russia because of our obligations.

There is already a NATO-Ukraine Commission.  Ukraine is involved in the NATO Afghanistan mission.  It is “the first partner country to contribute to the NATO-led counter-piracy operation Ocean Shield.”  All this is a reminder that organisations everywhere tend to want to expand, and that the sum of all these special initiatives and arrangements is that NATO would rather like Ukraine to join it.  No wonder that a few years ago Ukraine sent an official letter of application for Membership Action Plan – the first step in joining.

Putin is evidently determined to maintain his grip on the Ukraine, a country that is uneasily divided between a Russia-leaning east and an EU-leaning west.  That the EU failed to put its money where its mouth is over trade, thus helping to spark the present crisis, shouldn’t prevent the western world from stepping up sanctions if Putin further violates Ukraine’s sovereignty.  (Yes, Crimea only joined the Ukraine relatively recently; but no, Russia is not entitled in effect to tear if off again by force.)  But there is a limit to what we can do for Ukraine, and it falls far short of military action.

That we are, thankfully, not committed to take up arms in defence of a country which is deeply divided, during a crisis for which Russia is not solely responsible, and which has no strategic interest for Britain that would justify military action is worth reflecting on.  It is also worth having a glance at the list of other NATO members that we are committed to under the terms of Article 5.  They include Latvia, Lithuania and Estonia. Were Russia ever to invade them, Britain’s voters just might claim they were never consulted about the commitment to go to war on those countries’ behalf.

NATO is in principle a good thing – and we are accustomed to thinking that it’s a good thing because of the indispensable role that it played during the Cold War.  But the Ukraine imbroglio is a reminder that there should be much more clear and open debate about its future, in Britain and elsewhere.  (Perhaps the candidates for the vacant Defence Select Committee chairmanship could oblige.)  It should not be allowed to drift towards expansion without some very hard questions being asked about how far east its canopy should stretch, and which countries we are prepared militarily to defend.