But it looks as if the tanks are a no-go. The Germans cancelled theirs. 

What was that title of some stupid movie - the Forever War. Creating crises is the 'Crats' specialty. Ending them (through surgical application of military force) is the U.S. tradition through two centuries at least. 

There is some indication that the nation wants to move back toward the latter policies - aka Peace Through Strength. That is a time-honored thing going back to antiquity. Great powers have always dealt in that when they could. It's a civilized use of power - possibly one of the most-civilized. Weak leaders/nations cannot employ it because it requires demonstrating to enemies (and potential enemies) a willingness and enjoyment of the use of superior firepower.  

If Zelensky believes he will be denied nothing, he has little incentive to negotiate peace at any point, because he can (theoretically) improve his side's strategic position by holding out as long as possible before negotiating. 

This is Ockaham's Razor applied to warfare.