After seven weeks of protests by students and workers demanding democratic change and the end of corruption, soldiers and tanks chased and killed demonstrators and onlookers in the streets leading to Beijing's Tiananmen Square on June 4 1989.

Hundreds, or possibly more than 1,000, were killed, although the precise number of deaths remains unknown.

"That incident was a political turbulence and the central government took measures to stop the turbulence which is a correct policy," Chinese defence minister General Wei Fenghe told a regional security forum in Singapore.

Wei asked why people still say that China "did not handle the incident properly".

"The 30 years have proven that China has undergone major changes," he said, adding that because of the government's action at that time "China has enjoyed stability and development".

Inside China an army of online censors have scrubbed clean social media, removing articles, memes, hash-tags or photos alluding to the Tiananmen crackdown.

Discussions of the 1989 pro-democracy protests and their brutal suppression are strictly taboo, and authorities have rounded up or warned activists, lawyers and journalists ahead of the anniversary each year.

Talking privately with family and friends about Tiananmen is possible, but any commemoration in public risks almost certain arrest.

'Resolve and will'

In a wide-ranging speech that came a day after acting US Secretary of Defense Patrick Shanahan addressed the same forum, Wei vowed that China will not be bullied by the United States, issuing a combative defence of its policies on Taiwan, the South China Sea and the restive region of Xinjiang.

Washington and Beijing have been vying for influence in the Asia Pacific region, which hosts potential flashpoints such as the South China Sea, the Korean Peninsula and the Taiwan Strait.

China will not renounce the use of force in the reunification of self-ruled Taiwan, calling it "very dangerous" to underestimate Beijing's will.

"We will strive for the process of peaceful reunification with utmost sincerity and greatest efforts but we make no promise to renounce the use of force," he said.

The two sides have been ruled separately since the end of a civil war on the mainland in 1949 but China still sees Taiwan as part of its territory to be reunified one day.

"Any underestimation of the PLA's (People's Liberation Army) resolve and will is extremely dangerous," he added, calling it the army's "sacred duty" to defend Chinese territory.

In his speech on Saturday, Shanahan told the forum that Washington will continue to make military expertise and equipment available to Taiwan for its self-defence.

"This support empowers the people of Taiwan to determine their own future," Shanahan said.

Any resolution of differences must not be done with coercion, he added.