Germany's cowardly facade begins to crack. First Poland, then the other European countries such as Spain, Denmark and Finland that have them. Lastly, the Germans will themselves supply them. At a minimum, Ukraine needs 100 western battle tanks in this class, including Challenger 2s. Maybe 150. Ideally 300 to help push the Russians out of northeast and then eastern Ukraine, with their occupation of Crimea unsustainable thereafter.
Tanks, plus missile delivery systems (eg Panzerhaubitze 2000, Caesar and HIMARS), other armoured vehicles (eg Bradley and Marder vehicles), drones, helicopters, jets (eg F-16s from the Netherlands), Ukrainian knowhow and spirit, of course.
Putin must lose and be seen to lose to cure Russia of the cancer of his aggressive doctrine.