Nord Stream 2 also risks exposing divides in German Chancellor Olaf Scholz’s coalition government.
The Greens have long been opposed to the pipeline but Mr Scholz has said the pipeline should not be made into a political issue.
German Foreign Minister Annalena Baerbock, who led the Greens in last year’s elections, held talks with Antony Blinken, the US Secretary of State.
Mr Blinken said that the pipeline’s future would be at risk if Russia, which has amassed 100,000 troops at the border, invaded Ukraine.
He said. “This pipeline does not have gas flowing through it at present and if Russia renews its aggression toward Ukraine, it would certainly be difficult to see gas flowing through it in the future.
“So some may see Nord Stream Two as leverage that Russia can use against Europe. In fact, it’s leverage for Europe to use against Russia.”
Mr Blinken has also moved to calm EU fears that the summit with Mr Putin would cut European allies out of any decisions over Ukraine’s future.
“President Biden has made absolutely clear to President Putin [that] when it comes to questions of European security, there is going to be nothing about Europe without Europe, not just full coordination, full consultation, but participation as well,” he said.
Ursula von der Leyen, the European Commission president said on Friday, “One thing is clear – no solution without Europe. No matter the solution, it will have to go through Europe.”