When the White House began negotiating with Ukraine to provide it for the first time with some of America’s most powerful, precision-guided weapons, U.S. President Joe Biden insisted that Ukrainian President Volodymyr Zelenskyy agree to one major restriction: No firing into Russian territory, no matter how great the provocation.

"Ukrainians have given us assurance that they will not use these systems against targets on Russian territory,’’ Secretary of State Antony Blinken told reporters Wednesday, with the secretary-general of NATO standing alongside him. But he immediately added that Russia was the only one to blame for the introduction of a powerful new weapon to the battlefield. "The best way to avoid escalation is Russia to stop the aggression and the war that it started.”

There is no question that the decision to give Zelenskyy the weapons he has requested for weeks, intended to target Russian command posts and staging areas inside Ukraine, marked a major escalation in the kind of military aid that Washington is providing to help kill Russian forces.