The measurements of the event
The missile came down at about 04.00 local time in a field near the village of Tarnawa-Kolonia, close to Lublin, leaving a crater 10 metres wide. The point of impact lies about 80km inside the Ukrainian border. Prime Minister Donald Tusk said the munition was most likely Russian and that analysis pointed to a Kh-101 cruise missile.[1]
Poland scrambled fighter jets during the attack. Tusk said there was no reason to believe Poland had been targeted and that the military stood ready to intercept had the missile threatened populated areas. The munition was not engaged, and no one was hurt at the site.[1]
The threshold of engagement
Tusk's sentence in fact states a rule. Engagement is tied not to a munition entering alliance territory but to its threatening populated areas. Once that threshold is chosen, a cruise missile coming down unengaged 80km inside the border stops being a malfunction and becomes the outcome the system is designed to produce.[1]
That threshold will not wait long to be tested. If another munition enters the airspace of NATO member Poland before 31 October, the question to answer is whether it is engaged in the air; if it is again found in a field, the rule will have shown itself to be the practice rather than the exception.[1]
The load the declaration carries
NATO's Supreme Allied Commander Europe, Gen Alexus Grynkewich, said the alliance would continue to take all necessary measures to defend NATO territory. That is a declaration of commitment, and a declaration works only if the other side finds it credible. Unlike capability, a declaration cannot be counted; it can only be tested.[1]
There may be an engineering reason for the restraint: an intercept over sparsely populated ground creates its own harm through falling debris, and the choice need not indicate a gap in capability. What the other side observes is this: aircraft in the air, a line along which nothing was fired, and a crater in a field.[1]