It is up to the Chinese people to resolve the Taiwan issue, and China will never renounce the right to use force but will strive for a peaceful resolution, President Xi Jinping said on Sunday at the opening of a major party meeting.
China views democratically , despite the strong objections of the government in Taipei, which rejects the sovereignty claims and says only the island's people have the right to decide their future.
Tensions rose dramatically in August after China staged war games near Taiwan following the visit to Taipei of US House Speaker Nancy Pelosi.
Those military activities have continued though at a reduced pace.
Delegates applaud as Chinese President Xi Jinping arrives at the opening ceremony of the 20th National Congress of China's ruling Communist Party in Beijing. Source: AAP / Mark Schiefelbein/AP
"Resolving the Taiwan issue is the Chinese people's own business, and it is up to the Chinese people to decide," he said.
"We insist on striving for the prospect of peaceful reunification with the greatest sincerity and best efforts, but we will never promise to give up the use of force and reserve the option to take all necessary measures."
That option is aimed at "interference" by external forces and a "very small number" of Taiwan independence supporters rather than the vast majority of the Taiwanese people, Mr Xi said.
"The historical wheels of national reunification and national rejuvenation are rolling forward, and the complete reunification of the motherland must be achieved, and it must be achieved!" he added to a long round of applause.
In her national day speech on Monday, Taiwan President Tsai Ing-wen said war between Taiwan and China was "absolutely not an option" and reiterated her willingness to talk to Beijing.
China refuses to speak to Ms Tsai, considering her a separatist.
Beijing has offered Taiwan a "one country, two systems" model of autonomy, the same formula it uses for Hong Kong.
But all mainstream Taiwanese political parties have rejected that proposal, and it has almost no public support, according to opinion polls.
Mr Xi also told the congress China must ensure Hong Kong is ruled by patriots and it will support Hong Kong in integrating with the mainland.
"One country, two systems" is the best system for Hong Kong and must be adhered to in the long run, he said.
