The Kremlin is determined to isolate Ukraine, which means not only breaking the will of the country’s backers, but also cutting it off physically by striking merchant ships, ports, and border crossings. These assaults cannot go unanswered, because they embolden Russian President Vladimir Putin to continue testing the West.

LVIV—Jet-powered Russian drones recently hit a train in Ukraine a mere mile from the Polish border. The drone pilots, and their Kremlin minders, must have known that officials from Europe, the United Kingdom, the United States, and elsewhere had previously left Kyiv by train after participating in the Yalta European Strategy (YES) Annual Meeting, a sort of Ukrainian Davos. But the trains carrying former UK Prime Minister Boris Johnson, former Swedish Prime Minister Carl Bildt, former CIA Director David Petraeus, and former Polish President Aleksander Kwaśniewski, among others, were not hit. Had the Russians missed them intentionally or through incompetence?