BERLIN—The United States must not determine European energy policy or decide whether Germany buys Russian gas, a top German diplomat said on Oct. 16.

Foreign Ministry State Secretary Andreas Michaelis said Russia would remain a key energy supplier for Europe, regardless of U.S. pressure on the issue.

“This is part of European core interests,” Michaelis told a conference on transatlantic ties hosted by the Aspen Institute think tank. “I don’t want European energy policy to be defined in Washington.”

U.S. President Donald Trump has criticized Germany for supporting the Nord Stream 2 gas pipeline project, which will transport Russian gas to Germany, accusing Germany of being a “captive” of Russia due to its energy reliance.

Some European countries also oppose the project, which is led by Russian gas giant Gazprom and financed by five Western companies, but Michaelis said it was a matter of national sovereignty.

“We need to consult the European partners. We need to have a sound model that works,” he said. “But I’m certainly not willing to accept that Washington is deciding at the end of the day that we should not rely on Russian gas and that we should not complete this pipeline project,” he said.

The German government said last week it continues to regard the Nord Stream 2 pipeline as a useful project, given that it expects Germany’s gas demand to increase over coming years.

Germany, however, is also pressing to ensure that Ukraine is able to maintain a role as a gas transit country once the Russian-backed undersea pipeline is complete.

Michaelis said Germany was boosting its contribution to NATO and European security, in line with demands from Washington, but a more balanced transatlantic relationship also required Berlin to speak out when there were areas of disagreement, such as over the U.S. withdrawal from the 2015 Iran nuclear deal.

He said some policymakers in Washington were realizing that Europe needed more “room to breathe” with regard to the nuclear deal, particularly on the financing front, adding that he was not aware that the U.S. government was moving toward imposing sanctions on the Belgium-based SWIFT global payment network.

He said European diplomats were focused on the need to facilitate business transactions permitted under U.S. sanctions against Iran, for instance involving humanitarian aid, an argument that was starting to resonate in Washington.