"I regret that the joint approach of Europe and the United States on Russia and sanctions has been undermined and abandoned in this way," Zypries told Reuters in an interview.
Zypries, a senior member of the center-left Social Democrats, said it remains to be seen if U.S. President Donald Trump would approve the senators' proposal to sanction European firms that take part in or finance energy projects like the Nord Stream 2 gas pipeline.
"If he does, we'll have to consider what we are going to do against it," Zypries added.
Among the firms that are involved in the Nord Stream 2 project are subsidiaries of Germany's chemicals maker BASF Group and power and gas distributor E.ON.
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