Xi Jinping marked the centennial of the Chinese Communist party’s founding on Thursday with a nationalistic address in Beijing, warning that any infringements on the country’s sovereignty would be met by a “great wall of steel”.

But the Chinese president’s hour-long address unveiled no new initiatives or timelines for the party’s most important policy objectives, such as reunification with Taiwan. Xi focused instead on the party’s role in accomplishing “the great rejuvenation of the Chinese nation”.

“We must uphold the firm leadership of the party,” Xi said. “China’s success hinges on the party.”

Xinhua, China’s official news agency, said 70,000 people attended Thursday’s ceremony. Most were government and party officials, soldiers, employees of state-owned enterprises and students.

The crowd was largely subdued but roared to life when Xi said China “will not tolerate sanctimonious preaching from those who think they have the right to lecture us”. The Chinese president added that unification with Taiwan remained “a historic mission and unshakeable commitment of the Chinese Communist party”.

The Financial Times has reported that the US and Japan have been secretly conducting joint war games aimed at repelling a Chinese invasion of Taiwan, which has been self-ruled since the Communist party’s Nationalist rivals fled to the island in 1949.

“The fact that there was no timeline [for unification] or change in rhetorical framing was positive for Taiwan,” said Margaret Lewis, a professor at Seton Hall Law School who is based in Taipei. But she noted that Xi has previously said Taiwan is “not a problem that can be passed from generation to generation”.

Xi is widely regarded as the country’s most powerful leader in decades and appeared on the rostrum of Tiananmen gate, where Mao Zedong declared the establishment of the People’s Republic of China 72 years ago. The president wore a grey Mao suit, setting him apart from other senior party cadres dressed in western business suits and ties.

Echoing Mao’s comments at the same spot in 1949, Xi said the Communist party’s victory “showed the world that the Chinese nation had stood up — the time when the Chinese people could be bullied by others was gone forever”. The party, he added, remained “the backbone of the nation”.

Xi’s speech was the culmination of a series of celebratory events that began on Monday with a mass performance at Beijing’s Olympic stadium.

His administration has routinely marked patriotic anniversaries with large parades and military displays, including the 70th anniversaries of the party’s victory over its Nationalist rivals and the end of the second world war.

This week’s events commemorating the party’s centennial were the first since the outbreak of the coronavirus pandemic in Wuhan 18 months ago. The party has hailed its success in containing Covid-19 as evidence of the “superiority” of its political and economic systems compared with those of western democracies, despite criticism of its early handling of the health crisis.

Security across Beijing was tight in the run-up to the celebrations. Journalists covering Xi’s speech were forced to quarantine for 24 hours in advance and had to take two Covid-19 tests before being bussed to Tiananmen Square at 3am.

Those admitted to VIP areas close to top party leaders had to undergo week-long home quarantines ahead of the event.

Thursday also marked the 24th anniversary of China’s resumption of sovereignty over Hong Kong from the UK.

The handover is traditionally remembered with large protests by the territory’s pro-democracy camp. But Hong Kong police refused to grant protest organisers permission to gather this year.

Dozens of leading democratic activists are in prison awaiting trial on charges under a sweeping national security law imposed on the territory last year by China’s parliament.

John Lee, Hong Kong’s chief secretary, said the national security law had made the city more secure. “Hong Kong is now safe again . . . citizen’s lives will return to normal, society will resume operations and the economy can be revived,” he said.

Additional reporting by Xinning Liu in Beijing and Nicolle Liu in Hong Kong