Russia and Germany have reacted angrily to sanctions approved by President Donald Trump on the Nord Stream 2 gas pipeline between the two countries.
The sanctions target companies building the undersea pipeline that will allow Russia to increase gas exports to Germany.
The US considers it a security risk.
However, Germany accused Washington of interfering in its internal affairs, while Russia and EU officials also criticized the sanctions.
Congress voted through the measures as part of a defense bill last week and the legislation, which described the pipeline as a “tool of coercion”, was signed off by President Trump on December 20.
The almost $11 billion Nord Stream 2 project has infuriated the US, with both Republican and Democratic lawmakers opposing it.
The Trump administration fears the pipeline will tighten Russia’s grip over Europe’s energy supply and reduce its own share of the lucrative European market for American liquefied natural gas.
President Trump has said the 1,225km (760-mile) pipeline, owned by Russia’s state-owned gas company, Gazprom, could turn Germany into a “hostage of Russia”.
Speaking on German TV, Finance Minister Olaf Scholz said the sanctions were an infringement of sovereignty.
He said: “It is up to the companies involved in the construction of the pipeline to take the next decisions.”
German Foreign Minister Heiko Maas has said the sanctions amount to “interference in autonomous decisions taken in Europe”.
The US sanctions have also angered Russia and the EU, which says it should be able to decide its own energy policies.
An EU spokesman told AFP on December 21: “As a matter of principle, the EU opposes the imposition of sanctions against EU companies conducting legitimate business.”
Russia’s foreign ministry also strongly opposed the move, with ministry spokeswoman Maria Zakharova accusing Washington of promoting an “ideology” that hinders global competition.
The consortium behind Nord Stream 2 confirmed that it would build the pipeline as soon as possible, despite the sanctions.
It said: “Completing the project is essential for European supply security. We, together with the companies supporting the project, will work on finishing the pipeline as soon as possible.”
However, Allseas, a Swiss-Dutch company involved in the project, said it had suspended its pipe-laying activities in anticipation of the sanctions.
Russia currently supplies about 40% of the EU’s gas supplies – just ahead of Norway, which is not in the EU but takes part in its single market. Nord Stream 2 will increase the amount of gas going under the Baltic to 55 billion cubic meters per year.