As former US secretary of state Henry Kissinger was missed and remembered in China after he passed away at the age of 100, his significant legacy in promoting China-United States relations was recalled by many of those who mourned the veteran US statesman.

Kissinger, who passed away on Wednesday at his home in the US state of Connecticut, was always called "an old friend of the Chinese people". He visited China more than 100 times following his secret trip to the country in 1971, which commenced the normalization of China-US relations.

Over the past half century and more, the veteran diplomat had been acting as a bridge between Beijing and Washington amid ups and downs in the two countries' relationship.

In a message of condolence sent to US President Joe Biden on Thursday over Kissinger's passing, President Xi Jinping said that Kissinger had made it his lifelong pursuit to promote the development of China-US relations and enhance the friendship between the two peoples, and "his name will always be associated with China-US relations".

Zhu Feng, executive dean of the School of International Relations at Nanjing University, said that Kissinger was a vital participant in normalizing Sino-US relations, a facilitator of bilateral cooperation and an advocate for enhancing the management and strategic stability of the relationship.

Kissinger was the only US diplomat who directly communicated and engaged in dialogue with top Chinese leaders of different generations — Mao Zedong, Deng Xiaoping, Jiang Zemin, Hu Jintao and Xi Jinping, and there was no one else who possessed the same balanced and profound understanding of China, Zhu said.

Although Kissinger had gradually withdrawn from US politics in the past two decades, he still remained an influential and significant figure in the development of Sino-US relations, Zhu added.

Kissinger's last visit to China took place in July, a crucial moment at which the countries' relations had hit a low amid increasing rivalry in the areas of security, technology and ideology, and international concerns about "decoupling", a new Cold War or even a military conflict between China and the US had grown stronger.

During that trip, the Chinese side gave Kissinger a high-level reception, and President Xi met with him at Villa No 5 of the Diaoyutai State Guesthouse in Beijing, where Kissinger and Premier Zhou Enlai had met to start the normalization of Sino-US relations.

"We will not forget the historical contributions you have made to the development of China-US relations and the friendship between the Chinese and American people," Xi told Kissinger.

Many Chinese internet users expressed their condolences over his passing, wishing him to rest in peace or posting candle icons. Some netizens described him as a "promoter of important historical processes" and a "witness and guardian" of Sino-US relations.

In 2011, Kissinger published the book On China, in which he pointed out that US leaders should seek to understand Chinese politics and history, but he implied that he had little confidence in this happening in the near future.

Oxford University China-specialist Rana Mitter, writing in the Guardian, called On China an "unusual and valuable book", saying that Kissinger was "one of the very few who made the American relationship with China the key axis for his world view".

Imran Khalid, a freelance columnist on international affairs, said that as it was grounded in realism and mutual respect, Kissinger's steadfast dedication to interacting with China served as a cornerstone for establishing diplomatic ties between the two nations.

In a period characterized by swift global changes and evolving power dynamics, Kissinger's sagacity continues to illuminate the path of reason, said Khalid in an opinion piece published on the website of the China Global Television Network on Thursday.

"His legacy acts as a reminder of the deep significance of diplomacy and advocates for a thoughtful, forward-looking approach to international relations."

The Foreign Ministry spoke highly of Kissinger's contributions to promoting China-US relations.

Ministry spokesman Wang Wenbin said on Thursday that Kissinger attached great importance to China-US relations, which he said are of vital significance to both China and the US and global peace and prosperity.

Both sides need to carry forward Kissinger's strategic vision, political courage and diplomatic wisdom and, as President Xi and President Biden agreed in San Francisco, uphold the principle of mutual respect, peaceful coexistence and win-win cooperation, and work to deliver a healthy, stable and sustainable China-US relationship.