SINGAPORE — China will not flinch from war if Taiwan takes a decisive step toward independence, and it does not trust the United States’ assertions that it opposes that course for the island, the Chinese defense minister warned on Sunday, a day after Defense Secretary Lloyd J. Austin III accused Beijing of increasingly bellicose activity near Taiwan.

The defense minister, Gen. Wei Fenghe, spoke on the last day of the Shangri-La Dialogue, a regional security forum in Singapore that Mr. Austin also attended. In their exchanges over the weekend, the two men have played out in miniature the tensions between Beijing and Washington over disputes across Asia, particularly over Taiwan.

In his speech to diplomats, defense officials and security experts at a five-star hotel, General Wei said that China was sincerely doing everything it could to bring about peaceful unification with Taiwan, the self-governed island that Beijing considers its own. But, he said, “no one should ever underestimate the resolve and capabilities of China’s armed forces” to defend its sovereignty claims.

“For the sake of unification, the United States fought the war between North and South,” General Wei said. “China is most unwilling to go through a civil war like that, but will resolutely smash any schemes for Taiwan independence. If anyone dares to split off Taiwan, we will not hesitate to fight, will not flinch from the cost, and will fight to the very end.”

China has long said that it would take Taiwan by force if necessary, and General Wei’s comments left plenty of uncertainty about what Xi Jinping and other leaders in Beijing would consider a threshold event that justified doing so. But the comments from General Wei, Mr. Austin and others at the Singapore meeting have underscored how Taiwan remains the most volatile point of contention between China and the United States and its allies.

Officials and experts disagree over how imminent a military clash over Taiwan might be. But most believe that the danger is rising as the People’s Liberation Army moves closer to amassing the equipment and skills needed to make invasion a plausible, if daunting and profoundly costly, option.

“You’re hearing more worries about Taiwan, more people saying that conflict is not a matter of if, but of when,” Natasha Kassam, a former Australian diplomat who is now a researcher at the Lowy Institute in Sydney, said in an interview in Singapore. “We’re entering more dangerous waters. But for China, an ability to start a full-scale invasion would be just part of the equation. How do you occupy an island of 24 million people?”

General Wei and Mr. Austin held talks on Friday that covered regional issues and the war in Ukraine, as well as efforts to strengthen communications between the American and Chinese militaries and avoid dangerous military misjudgments.

Mr. Austin told the forum on Saturday that China was engaged in “provocative and destabilizing” military activities near Taiwan. He also said that the Biden administration did not support Taiwan independence and remained committed to a “one China” principle, which acknowledges — but does not endorse — Beijing’s position on Taiwan.

On Sunday, General Wei indicated, without naming the United States, that Chinese leaders do not believe such reassurances.

“A certain country has violated the principle and commitments on ‘one China’ regarding the Taiwan issue,” General Wei said in his speech. “Taiwan independence is a dead end, a delusion. Leaning on the support of foreigners will not succeed. Forget about it.”

Since 1979, when it ended formal ties with Taiwan and extended diplomatic recognition to China, the United States has continued to sell arms to the island. U.S. law also requires that Washington be ready to “resist any resort to force” against Taiwan, leaving open the possibility that the American military could step in if China tried to invade.

Mr. Austin said in Singapore that the United States was committed to “maintaining our own capacity to resist any use of force or other forms of coercion” that could imperil Taiwan.

Chinese policymakers have accused the Biden administration, and President Donald J. Trump’s administration before it, of steadily upgrading its political and military support for Taiwan.

Beijing has expressed particular scorn for Tsai Ing-wen, the current president of Taiwan, who has rejected China’s preconditions for talks on the island’s future. Taiwan’s next presidential election, in 2024, could create another flash point. A growing number of people in Taiwan reject the idea that they are culturally and historically part of China, and an overwhelming majority say they do not accept Beijing’s framework for unification.

“We’ll defend our hard-won democracy,” the Taiwanese foreign ministry said on Saturday, responding to an earlier remark from General Wei that the People’s Liberation Army would “smash” any drive for Taiwanese independence. “History shows appeasement only invites aggression,” the ministry said.

In his Saturday speech, Mr. Austin blamed China for the current tensions over Taiwan, citing “an alarming increase in the number of unsafe aerial intercepts and confrontations at sea” by People’s Liberation Army planes and vessels. “The stakes are especially stark in the Taiwan Strait,” Mr. Austin said.

Richard Marles, the defense minister of Australia, told the Singapore forum that China should offer more reassurances about its military buildup. “Reassuring statecraft will be fundamental to peace and stability across the Taiwan Strait,” he said.

General Wei said it was “a historical and strategic mistake” for Washington to treat China as an adversary. He called on the United States to “stop attacking and smearing China” and to “stop interfering in China’s internal affairs.” Unless it does so, ties will not improve, General Wei added.

“If you want confrontation,” he said, “we will fight to the end.”