TOKYO -- Three decades have passed since the Chinese Communist Party resorted to bullets and tanks to silence unarmed demonstrators seeking democracy and an end to corruption in the heart of Beijing. From then and to its current leadership under President Xi Jinping, the party has taken the path of promoting economic growth, while tightening its grip on power and keeping a lid on any move toward political liberalization.

On the eve of the 30th anniversary of the Tiananmen Square crackdown, independent Hong Kong publisher New Century Press has published copies of transcripts of discussions by top party leaders and elders at the closed-door meetings in the immediate aftermath of June 4, 1989.

The book, "The Last Secret: The Final Documents from the June Fourth Crackdown," on shelves Friday is a collection of speeches by 17 people summoned to an extended meeting of the Politburo, the party's highest policymaking body, to spell out their full-hearted support to paramount leader Deng Xiaoping.

The book fills in previously unknown details about the discussions within the party elite leading up to a June 23-25 plenary session of the Central Committee. At that session, the party dismissed reform-minded General Secretary Zhao Ziyang and replaced him with Shanghai party secretary Jiang Zemin, setting China on its current path.

The Politburo meeting, held from June 19 to 21, was a smaller grouping meant to confirm a consensus among the top leadership before the plenary session and to show their loyalty to Deng, who commanded the military to quell the student movement.

All 17 speakers documented in the book, such as then-Vice President Wang Zhen and Marshal Nie Rongzhen, opened their remarks with "I completely agree with" or "I completely support" Deng's decision to mobilize the military. They also concurred with Premier Li Peng's report condemning Zhao, who opposed sending tanks into Tiananmen, for what was described as "anti-party, anti-socialism disturbance."

For example, the book documents Peng Zhen, the former chairman of the Standing Committee of the National People's Congress. "For some time, an extremely small group of people who stubbornly promoted bourgeois liberalization cooperated with foreign hostile forces to call... to tear down the cornerstones of our country."

These speeches were recorded and handed out to 489 members who attended the June 23-25 Central Committee session, but they were collected afterward to preserve the secrecy of the decision-making at the time.

Andrew Nathan, a political-science professor at Columbia University who wrote the book's preface, said the party learned hard lessons from the Tiananmen crackdown. "The party leadership drew lessons from the events that had taken place, and these lessons explain the mentality of Xi Jinping's government today," he told reporters in Tokyo on Friday.

Nathan, known for coediting "The Tiananmen Papers" published in 2001, said there were at least four lessons that the party and Xi may have extracted from the events of June 1989.

First, China feels that it is surrounded by hostile enemies at home and abroad who are always seeking to overthrow the regime. Second, the party leadership, therefore, must remain united so as not to be taken advantage of by these enemies. Third, the party cannot lose control over ideology, and fourth, to achieve all this, the party requires what it calls the hexin, or "core" leader.

Columbia University professor Andrew Nathan discusses the new book "The Last Secret: The Final Documents from the June Fourth Crackdown" in Tokyo on May 31. (Photo by Kenji Kawase)

Both Jiang and his successor, Hu Jintao, failed to establish their power to that extent. But Xi -- who in 1989 was the party leader in a district of Ningde in Fujian Province far from the capital at the time of the crackdown -- succeeded in being enshrined as the "core" in 2016, after further tightening control over civil society and eliminating his rivals through anti-corruption purges since taking power in 2012.

By 2018, he had abolished term limits in the constitution to allow himself to stay in power forever if he so chooses.

Hu Ping, a veteran activist and honorary editor of the New York-based pro-democracy journal Beijing Spring, told the Nikkei Asian Review that "the party is not able to continue on with this type of tight rule forever," but he does not foresee changes in the near future. As the Tiananmen crackdown has "lowered the bar of suppression," he said people's "mentality to resist has diminished" as a result.

Wang Dan, a former Tiananmen student leader now in exile in the U.S., remains optimistic about the prospects of democracy and regime change in China. He believes the magma of dissent is growing and "there will be another possible mass uprising" if economic conditions deteriorate, but did not predict when this would happen.

Nathan, an expert on China as well as human rights and democracy, said the chance of another mass uprising like 1989 "is not really great." On top of the lessons learned by the party, "the regime's technique of control is stronger and stronger due to information technology." China's development and deployment of surveillance cameras, facial recognition and social credit system -- in which citizens receive a score based on criteria like bad driving and spreading fake news -- make it "very difficult for citizens to get out of control."

What might shake the regime’s control? One scenario would be if the "leadership splits and somebody in the leadership uses demonstrations by citizens to support his struggle for power."

Nathan added, noting Xi’s breaking of norms about preparing to give way to another generation of party leaders: "I guess the most likely crisis for China to face at some time is a succession crisis…. Nothing in politics ever stays the same."