More than a million marchers flooded Hong Kong’s streets at the start of the week, far and away the biggest protests the territory has ever seen. An astonishing one-seventh of Hong Kong’s population turned out in opposition to a proposed law that would, for the first time, authorize extraditions to mainland China. If the bill is enacted, any resident of Hong Kong accused of an offense might be subjected to China’s grotesque and repressive judicial system, in which arbitrary detention and torture are common, and due process exists only at the pleasure of the ruling Communist Party.

The extradition bill is only the latest manifestation of the stakes involved in this struggle. The Chinese regime under Xi Jinping is intent on doing away with Hong Kong’s autonomy and way of life. Over the last few years, Beijing has been making it increasingly clear that it will allow nothing to stop it from dismantling culture of freedom and rule of law that have taken root in Hong Kong. That prospect rightly alarms and angers the city’s residents. If only it alarmed and angered the rest of the free world as well.

When Hong Kong was returned to Chinese control in 1997, Beijing solemnly vowed that economic and political rights in the formerly British-ruled enclave would remain inviolate until at least 2047. In a legally binding Joint Declaration, it stipulated that freedom “of speech, of the press, of assembly, of association, of travel, of movement, of correspondence, of strike, of choice of occupation, of academic research, and of religious belief” would “remain unchanged for 50 years.” That was the much-ballyhooed “one country, two systems” principle — the face-saving pretext on which Britain relied to justify putting millions of people under the sovereignty of a brutal tyranny.

But China, like all communist tyrannies, regards freedom of thought, political openness, and liberal norms as dangerous contagions. It never had any intention of preserving and protecting Hong Kong’s civil liberties. In recent years, notwithstanding the guarantees in the Joint Declaration, Beijing has “jailed activists, used the courts to disqualify democratically elected opposition lawmakers, expelled a foreign journalist, and banned a political party that advocated Hong Kong independence,” to quote a Wall Street Journal summary of developments in the city.

“One country, two systems” was always a dishonorable delusion. Britain’s surrender of Hong Kong was a shameful betrayal, as anyone should have seen at the time. But Western governments and corporations, in their ravenous hunger for access to the Chinese market, consistently turned a blind eye to Beijing’s repression, bad faith, and flouting of international standards. China, in turn, drew the logical conclusion — that it need not even pretend to uphold its commitment to Hong Kong’s freedoms. So it hasn’t: In 2017, the Chinese foreign ministry sneeringly declared the joint declaration “no longer has any practical significance.”

The enormous outcry against the extradition bill comes just days after the world marked the 30th anniversary of the Tiananmen Square massacre. Yet when it comes to human rights and the strangling of prodemocracy activism, nothing about China has changed since that bloody atrocity. Since 1989, the country has grown richer and stronger, but the regime is every bit as ruthless in its demand for absolute political power — and just as prepared to crush anyone who resists its grip.

Is it any wonder that residents of Hong Kong have reacted with such rage and fear, and in such immense numbers, to a proposal that would put their necks within the Communist Party’s grip? They know only too well what Beijing is capable of: A million ethnic Uighurs packed into concentration camps. The forcible harvesting of vital organs from prisoners of conscience. Endless cruelty and oppression in Tibet. The persecution unto death of even a Nobel peace laureate. A vast, asphyxiating machinery of online censorship. Institutionalized torture and slave labor. The utter denial of all political rights.

But Hong Kong’s people are on their own. The Western democracies will do nothing to help them. For decades, the political and economic leaders of the free world have generally averted their gaze from China’s depredations, preferring to cooperate with Beijing’s barbarism rather than to challenge it. That has been true especially of American presidents, as Democrats and Republicans alike have refused to pressure Beijing over its grisly human-rights crimes.

After the Tiananmen massacre, George H. W. Bush secretly dispatched two top aides to assure Deng Xiaoping that business could proceed as usual. Though Bill Clinton condemned Bush for “coddling dictators,” once in office he hailed China as a “strategic partner,” and announced that human rights would be “de-linked” from trade. Chinese dissidents pleaded in vain with Barack Obama to speak out against Xi Jinping’s pitiless crackdown on dissenters, but the Obama administration had other priorities. And while Donald Trump has enthusiastically gone after China on trade, he has shown no more interest than his predecessors in the Chinese government’s repression of Chinese citizens.

Asked on Wednesday about the turmoil in Hong Kong, President Trump said merely that he was “sure they will be able to work it out.” That was another way of assuring Beijing there will be no pushback from Washington. A million protesters cry out in desperation, but the world isn’t listening. Hong Kong is still free, but not for much longer.

(Jeff Jacoby is a columnist for The Boston Globe).