Russia can close the valves and noone can do anything. But russia would want the valves to be the only obstacle between their gas and germany, so germany would

Russia can close the valves and noone can do anything. But russia would want the valves to be the only obstacle between their gas and germany, so germany would always have an option to sit down with russia, make some kind of a deal, and the same day, gas could be reopened. Now, with the pipes destroyed, it will probably take months to fix them, and even if people in germany protest against their governments, the talks with russa are pointless. On the other hand, USA will sell a lot of very overpriced gas now to quite a few EU states.