This would have been quite the test for the Biden administration. I'm honestly curious what action they would have taken had it succeeded.
The U.S. is not a free country if its people have to live in fear of foreign dictators and theocrats. Had she been kidnapped or hurt, Biden would be right to respond with military force against everyone responsible.
On the other hand, the German government has almost no power to project force abroad so it might not matter much (aside from some sanctions or whatever).