The United States opened a new air defence base in northern Poland on Wednesday, an event the European nation's president said showed the country was secure as a member of NATO even as Russia wages war in neighbouring Ukraine.

"The Polish-American alliance is strong, regardless of who governs in Warsaw and Washington," Polish Foreign Minister Radoslaw Sikorski said.

The base, known as 'Aegis Ashore', is part of the North Atlantic Treaty Organization (NATO)'s broader missile shield.

The United States will officially open a new air defence base in northern Poland on Wednesday, as Warsaw seeks to reassure citizens that NATO guarantees their security amid jitters after Donald Trump's presidential election victory.

The Kremlin has hit out at the U.S. after it opened a new missile base in NATO Nation Poland. Kremlin spokesperson said that the U.S. was moving it military close to Russian borders. He cited Vladimir Putin to claim that the U.