The ceremony was broadcast across the country.
Officially, the display was to celebrate the 90th anniversary of the creation of the People’s Liberation Army. But it was also the highlight of a week of political theater promoting Mr. Xi as a uniquely qualified politician whose elevated status as China’s “core” leader, endorsed by officials last year, should be entrenched at the party congress.
“These military parades could become a regular, institutionalized thing, but this one also has a special meaning this year,” said Deng Yuwen, a former editor at a party newspaper in Beijing who writes current affairs commentaries. “It’s meant to show that Xi Jinping firmly has the military in his grip, and nobody should have any illusions of challenging him.”
The congress will almost certainly give Mr. Xi, 64, a second, five-year term as the party general secretary and chairman of the commission that controls the military, and it will appoint a new team to work under him.
No exact date has been fixed for the congress. An annual legislative meeting early next year will also almost certainly give Mr. Xi five more years as state president.
Some experts have speculated that Mr. Xi may want to retain power after those terms end, although the constitution says he cannot stay on as president. There are no firm rules for maximum terms as party general secretary.
Mr. Xi has accompanied the demands for unity with a vivid warning to officials who step out of line. In the past week, he oversaw the abrupt purge of Sun Zhengcai, a one-time contender for promotion at the congress. Mr. Sun, 53, had been the party secretary of Chongqing, a city in southwest China, until his dismissal in mid-July.
The party announced last Monday that he was under investigation for violations of “discipline” — usually a euphemism for corruption — and Mr. Sun has since been pilloried in official media. Provincial leaders, including many with a shot at promotion, have called meetings to denounce Mr. Sun as a “tiger,” or corrupt senior official.
“At this point, we can’t say for sure he will be the last big tiger to be brought down before the opening of the party congress,” said Prof. Ding Xueliang, a political scientist at the Hong Kong University of Science and Technology who studies the…