US President Joe Biden is hosting leaders of the 32-nation transatlantic alliance for three days from Tuesday, as well as the leaders of Australia, Japan, New Zealand and South Korea.

NATO Secretary-General Jens Stoltenberg told a news conference ahead of the 75th anniversary summit that their inclusion "demonstrates that our security is not regional, our security is global".

"And that's clearly demonstrated in the war in Ukraine where Iran, North Korea, China are supporting and enabling Russia's illegal war of aggression against Ukraine," Stoltenberg said on Monday, according to a NATO transcript.

China's foreign ministry took aim at the defence group, which was founded in 1949 to provide collective security against the Soviet Union.

"NATO's so-called security is at the expense of other countries' security and its actions have brought extremely high security risks to the world and the region," foreign ministry spokesman Lin Jian told a regular news conference in Beijing.

"China is firmly opposed to NATO's smears and attacks on China, to its willingness to shift the blame onto others, as well as NATO's use of China as an excuse to move eastward into the Asia-Pacific and stir up regional tensions," he said.

NATO's leaders are gathering in Washington in the shadow of setbacks in Ukraine and electoral headwinds on both sides of the Atlantic.

Biden is fighting for his political life after a disastrous debate against his Republican presidential rival, NATO sceptic Donald Trump.

The star of the summit is set to be Ukrainian President Volodymyr Zelensky, who is looking for firm signs of support even though NATO will not be extending his country an invitation to join the bloc.