TOKYO -- When Margaret Thatcher visited Hong Kong in 1984, just after reaching an agreement with the Chinese on the return of Hong Kong, she attended a news conference where a reporter put a tough question to her.
"Prime Minister, two days ago you signed an agreement with China promising to deliver over 5 million people into the hands of a communist dictatorship," Emily Lau asked. "Is that morally defensible, or is it really true that in international politics the highest form of morality is one's own national interest?"
Lau is 68 today and an influential pro-democracy figure. At the news conference 36 years ago, she was saying it was wrong to return Hong Kong to a dictatorship without sufficiently protecting the territory's people, such as by granting them British nationality.
The British prime minister claimed that everyone in Hong Kong was hailing the joint declaration, and in a slightly cold manner, suggested that perhaps the reporter might be "the solitary exception."
The Iron Lady was assuring that there would be no problem because regardless of the political style of China's communist regime, even if it did reject democracy, the arrangement was that the way of life of Hong Kong people would be maintained for the foreseeable future. It was the origin of "One Country, Two Systems."
The young Lau was fearing a worst-case scenario.
On Tuesday, Lau's concerns became a reality. The Hong Kong national security law, a piece of legislation that shakes the foundations of the "One Country, Two Systems" arrangement, was enacted in China's capital, Beijing, bypassing Hong Kong's own legislature.
Symbolically, the controversial law came into force hours before the 23rd anniversary of Hong Kong's return.
Lau went on to be chairperson of the Democratic Party and was herself called Hong Kong's "Iron Lady."
Back in mid-January, on a slightly chilly day in Hong Kong, Lau gave an interview to Nikkei. "Freedom and democracy. These are not given by heaven but something that we win by ourselves and must protect," she said. There must be a persistent effort, she stressed.
Her words came two months after pro-democracy forces won a resounding victory in Hong Kong district council elections.
Over in Taiwan, incumbent President Tsai Ing-wen of the pro-independence Democratic Progressive Party had just secured a second term in a landslide electoral victory.
For people like Lau, hope filled the air. Lau had her eye on September 2020 elections for the Legislative Council, Hong Kong's parliament, and was optimistic that young people's participation in politics and elections could lead to changes, not only in Hong Kong but in the rest of the world.
But the situation took an unexpected turn.
Only several days after the interview, the Chinese city of Wuhan, in Hubei Province, was locked down due to the novel coronavirus outbreak. The virus spread overseas, causing political, economic and social turmoil around the world.
And it was amid that turmoil that on May 28, China's National People's Congress adopted a measure that kick-started the process of introducing the national security law for Hong Kong. The law was passed and enacted by the Standing Committee of the National People's Congress on Tuesday.
"National security" is a concept that is important to Chinese President Xi Jinping.
In the autumn of 2013, the establishment of a National Security Commission was decided at a key meeting of the Chinese Communist Party. The commission was formally inaugurated the following January.
On July 1, 2015, a new national security law was enacted in China. It called for compliance with national security policies in various fields, including government, territories, the economy and the internet.
The fact that the law was enacted on July 1, the anniversary of Hong Kong's return, hinted that it was also aimed at Hong Kong. Residents of the territory may have not realized this at the time.
The new Hong Kong national security law of 2020 stipulates that a committee for safeguarding national security will be established in the territory and will enforce Xi's style of security, regardless of the "high degree of autonomy" promised to Hong Kong.
Under a mainland-style clampdown, incidents like the disappearance of Hong Kong booksellers in 2015 would be natural.
In the Causeway Bay Books incident, people related to the store -- which was known for publishing and selling books about scandals involving Xi and other Chinese dignitaries -- disappeared one after the other.
It was later found that five people had been spirited away to the mainland by Chinese authorities.
With the introduction of the new law, similar apprehensions are expected to be legalized. The wording of the law, disclosed late Tuesday, shows that in serious cases suspects could be extradited to the mainland and be imprisoned for life.
Iron lady Thatcher died seven years ago at the age of 87. The Sino-U.K. joint declaration that she described as being welcomed by everyone was essentially pronounced dead by the Chinese in 2017. The joint declaration, a Chinese Foreign Ministry official said at the time, "no longer has any realistic meaning."
Margaret Thatcher was wrong, and Emily Lau was right.
Belatedly, the British government is now seeking to expand its preferential treatment of Hong Kong's British National Overseas passport holders, allowing them to visit the U.K. more easily and providing them with "a path to citizenship."
Thatcher's counterpart in signing the Sino-U.K. joint declaration was Zhao Ziyang, then serving as Chinese premier. The enlightened reformer later became party general secretary.
Five years after the two iron ladies faced off in that historic news conference, Beijing showed the world it would not hesitate to quash peaceful demonstrations with military force. It did just that on June 4, 1989, in Tiananmen Square.
Zhao was condemned within the party for being sympathetic to the student movement and fell from power after the incident. He died in 2005 after spending many years under house arrest.
Feeling anxious about the future of "One country, Two systems," a demonstration has been held in the central part of Hong Kong on June 4 every year since the crackdown.
Or at least they had been. This year's event was not permitted. A peaceful demonstration was also rejected for the July 1 anniversary.
If Margaret Thatcher were still alive, how would she have complained to the Chinese about violating their pledge?
Katsuji Nakazawa is a Tokyo-based senior staff writer and editorial writer at Nikkei. He has spent seven years in China as a correspondent and later as China bureau chief. He is the 2014 recipient of the Vaughn-Ueda International Journalist prize for international reporting.