Calling the US plan "an evident product of its Cold-War mentality," ambassadors Anatoly Antonov of Russia and Qin Gang of China said the December 9-10 event would "stoke up ideological confrontation and a rift in the world, creating new 'dividing lines.'"

The summit is meant to fulfill a campaign pledge by Biden to advance the cause of global democracy at a time when autocratic governments have been on the rise.

But when the State Department on Tuesday published a list of about 110 invited countries -- without including Russia or China -- their reaction was furious.

China was especially angered by the inclusion of Taiwan, over which it claims sovereignty.

Writing on the website of conservative journal National Interest, the two ambassadors to the United States said democracy "can be realized in multiple ways, and no model can fit all countries." 

"No country has the right to judge the world's vast and varied political landscape by a single yardstick," the ambassadors added.

The article described communist China as having "an extensive, whole-process socialist democracy (which) reflects the people's will, suits the country's realities, and enjoys strong support from the people."

"It has been proved that the whole-process democracy works in China, and works very well."

The article did not mention Taiwan.

It said that Russia -- where long-serving President Vladimir Putin in April signed a law that could allow him to remain in power until 2036 -- is a "democratic federative law-governed state with a republican form of government" with century-old parliamentary traditions.

Without naming the United States, the envoys said that wars and conflicts launched in the name of spreading democracy, "severely undermine regional and international peace, security, and stability."

"Bombings of Yugoslavia, military intervention in Iraq, Afghanistan, and Libya, and 'democratic transformation' do nothing but harm," they wrote.

"Countries should focus on running their own affairs well, not condescendingly criticizing others."

They concluded by saying that countries should practice mutual respect and cooperation.

Such cooperation should rely heavily on the United Nations, they wrote, adding, "There should be a more inclusive global governance, not something like 'might makes right.'"

Among countries invited to the virtual summit are some where democracy appears fragile, has suffered setbacks, or where autocratic trends have emerged.

The invitees include Brazil, India and Pakistan but not Hungary or NATO member Turkey.