In Washington for the 75th anniversary summit of the alliance, the top diplomat of its newest member said a NATO without the United States would be "unthinkable" and lack credibility.

"If you want your partner to think about the things you think are a problem, you have to show commitment to their problems, and the American people are more concerned with the threat that China poses than Russia, for obvious reasons," Foreign Minister Tobias Billstrom said.

The alliance needs to keep facing Russia but Asia "should also be recognized as part of NATO's concerns, headaches," he said at the Carnegie Endowment for International Peace.

Billstrom said that Sweden -- which turned the page on two centuries of military non-alignment and joined NATO after Russia's invasion of Ukraine -- threw support behind the alliance opening a liaison office in Tokyo.

France has been the main opponent of such an office, arguing that the North Atlantic Treaty Organization is limited in geographic scope and can rely on allies' embassies if it needs to coordinate.

Trump, who is seeking to return to the White House, has repeatedly called NATO an unfair burden to the United States, with some of his advisors arguing that Ukraine is a distraction from a larger challenge of China.

President Joe Biden has encouraged a greater focus by NATO on Asia and invited the leaders of Japan, South Korea, Australia and New Zealand to the summit in Washington.

China earlier Tuesday lashed out at NATO, with foreign ministry spokesman Lin Jian accusing the alliance of using "China as an excuse to move eastward into the Asia-Pacific and stir up regional tensions."

NATO Secretary-General Jens Stoltenberg ahead of the summit renewed charges that China is supporting Russia's war in Ukraine through exports to Moscow's defense industry.