Ukrainian President Volodymyr Zelensky’s unscheduled appearance at Asia’s biggest security conference dominated proceedings on Sunday after China’s defence chief slammed “separatists” in Taiwan, drawing a sharp response from the government in Taipei.

Dressed in his trademark olive green T-shirt, Zelensky addressed the last day of the Shangri-La Dialogue forum in Singapore, asking for support and participation at a summit in Switzerland later this month aimed at bringing peace to his war-ravaged nation.

“We are convinced that our world wants to be united and be capable of acting in complete harmony,” he said to a ballroom packed with delegates in formal business wear and military uniforms.

Zelensky told a news conference that he was not able to meet the Chinese delegation at the conference and was disappointed that Beijing would not attend the summit.

“China, unfortunately... is working for countries not to come to the peace summit,” he said.

Earlier, China’s defence chief Dong Jun warned that prospects of a peaceful “reunification” of Taiwan were being eroded, and promised to ensure the island would never gain independence.

China views democratically governed Taiwan as its own territory, over the strong objections of the government in Taipei, and last month staged war games around the island in anger at the inauguration of President Lai Ching-te, who Beijing calls a “separatist”.

“Those separatists recently made fanatical statements that show their betrayal of the Chinese nation and their ancestors. They will be nailed to the pillar of shame in history,” Dong said.

He added that although China was committed to peaceful reunification with Taiwan, the People’s Liberation Army “will remain a strong force for upholding national reunification”.

Taiwan’s China-policy making Mainland Affairs Council said in response that it deeply regretted the “provocative and irrational” comments, and reiterated that the People’s Republic of China has never ruled the island.

China has repeatedly threatened force against Taiwan at international venues, and its threats violate the United Nations charter, the council said in a statement.

A US official, speaking on condition of anonymity because of the sensitivity of the matter, said Dong’s speech covered little new ground.

“Every year for three years, a new Chinese defence minister has come to Shangri-La,” the official said. “And every year, they’ve given a speech at complete odds with the reality of the PLA’s coercive activity across the region. This year was no different.”

Dong’s speech came a day after US defence secretary Lloyd Austin told delegates the Indo-Pacific region remained a key focus for the US, even as it grappled with security assistance for Ukraine and the war in Gaza.