Despite his caveats, Simon Tisdall is in effect making a case for Nato to go to war with Russia (“Defeat for Ukraine would be a global disaster. Nato must finally step in”, Foreign Affairs Commentary).
I believe that such a course of action would prove detrimental to western interests. If the Ukrainian counteroffensive fails to attain its ambitious objectives, no amount of western aid will allow Kyiv to prevail – including the controversial cluster munitions, that Washington is making available to the Ukrainians at the expense of its own soft power. The real choice facing the west is between a direct involvement of Nato and an end to hostilities through a peace treaty or an armistice of indefinite duration.