The war hawks answer would be so that we can economically separate russia-germany so that germany is more willing to go against russia. If Germany is dependent on gas from Russia they are less willing to risk their relationship.

At the time, Germany was on the fence about sanctions because they were getting gas via the Nordstream from Russia and didn't want to endanger that. Sudden, completely unexpected lack of gas from Russia = no impediment to backing sanctions. And that's how it turned out.

German industry was seen as competition by the US, and US didn't like Germany becoming economically tied with Russia.