The United States must reckon with Europe responding in kind if it declares "America First" and places its own economic interests before those of others, Germany's Economy Minister Peter Altmaier said.

In an interview with ARD television, Altmaier attributed the United States's desire to block the building of a new pipeline linking Russia and Germany under the Baltic Sea to its need to secure markets for its own liquid natural gas (LNG) exports.

"They have a large LNG terminal infrastructure to get value out of," said Altmaier, a close ally of Chancellor Angela Merkel, "but that LNG will be significantly pricier than pipeline gas, so blocking Nord Stream 2 will not on its own guarantee exports."

He added that Europe would respond firmly to US attempts to place its own economic interests before those of partners. "The US are our friends and partners, and we want to defend our common values.

"But if it's America first, and they put their economic interest before others, then they have to expect Europe to define their own interests and fight for them."