One day in 1955, the fledgling People's Republic of China was unhappy about U.S. involvement with Taiwan, the self-governing island that Beijing considered its territory. So Premier Zhou Enlai wrote a letter to the secretary-general of the United Nations.
"The Chinese people's exercise of their own sovereign rights in liberating their own territory," Zhou wrote, "is entirely a matter of China's internal affairs." He went on to use that wording, "internal affairs," three more times in the letter.
Internal affairs. Across the decades, from Zhou's relatively ineffectual plea extending to the dramatically different China that exists today, that precise phrase remains an indispensable tool for the Beijing government when challenges — and what it considers bad behavior — arrive from the outside.
Whether it's foreign complaints about human rights, disputes over the South China Sea or anything about Taiwan or Xinjiang or Tibet and the Dalai Lama, the answer has been remarkably consistent: These are the internal affairs of China — so keep your nose out of them.
For evidence, just review this past week's events and the Beijing government's reactions.
A U.S. basketball team's general manager supporting Hong Kong protesters with a single tweet from the United States? Interference in China's internal affairs, with major repercussions for the NBA. Apple hosting an app to help those protesters locate police? Interference in internal affairs.
An episode of "South Park" that skewers Hollywood for cozying up to Beijing? Close enough to interference in internal affairs to get the show scrubbed from the Chinese internet.
And U.S. sanctions on Chinese companies that Washington says provide technology to repress minorities in the country's predominantly Muslim Xinjiang region? No question about that one.
"I must point out that Xinjiang affairs are purely China's internal affairs that allow no foreign interference," Chinese Foreign Ministry spokesman Geng Shuang said Tuesday. "We urge the U.S. to correct its mistakes at once, withdraw this decision and stop its interference in China's internal affairs."
Ever since the Opium Wars in the mid-19th century, in which the British forced Qing Dynasty rulers into the opium trade and pried open Chinese ports to Western trade, China's government has been particularly sensitive to Western doings inside its borders.
But tension between internal and external in China is far older. The very language it uses for itself and the rest of humanity illustrates that: "zhongguo," or "middle country," for China and "waiguo," or "outside country," for the foreign.
Like any government that controls lots of far-flung land, China, whether run by imperial rulers, Nationalists or the Communist Party, has almost always functioned as a central government trying mightily to maintain control at the edges of a sprawling territory.
In the U.S., power is balanced carefully between a federal government and the states. In China, the might always comes back to the nucleus of the nucleus — once the emperor inside the Forbidden City, now Xi Jinping and the Communist Party's Politburo Standing Committee.
And in China's case, watching the farthest reaches of its territory for incursions is a strand of the fundamental, historical DNA.
This is, after all, a culture that, nearly a millennium ago, was invaded by Mongols who pushed in from its northern edge and formed the Yuan Dynasty, ruling for nearly a century before they collapsed and Han Chinese reclaimed power. The Great Wall, in fact, was built primarily to preserve China's territorial integrity by keeping more outsiders from invading.
Today, it's no accident that some of the Beijing government's most pressing worries are at the flanks of its domestic influence — Xinjiang and Tibet to the far west, Taiwan and now Hong Kong at its southeast edges.
But as this week's events underscore, a transformation has been taking place. With its growing influence and international profile, coupled with the rise in technology and the muddying of virtual borders, China's internal affairs are drifting into more external realms with each passing year.
The country's very success in some of its leadership's priorities — being taken seriously on an international stage and wielding influence worldwide — has placed what was once a relatively inward-focused government onto a global platform.
By opening up and engaging the world, China extended its reach everywhere. And where reach extends, so, too, has the communist government's insistence on control. Now the edges of that control have become less defined, because they are no longer entirely geographic or obvious.
For every step China takes into its vaunted Belt and Road initiative, designed to build global infrastructure and extend influence, it opens itself to more opinions, more disagreements, more potential contentiousness. That's simply the nature of international engagement.
For every fresh leap into the internet's choppy waters (even shielded by its "great firewall") and for every engagement with a Western tech behemoth like Apple, it creates opportunities for outsiders to trip over affairs that it might consider "internal."
For every move that its propaganda operations make toward framing themselves as sleek, independent media on a global stage, it thrusts itself into the marketplace of ideas and invites some of those ideas inside. And for every Confucius Institute it opens to promote Chinese culture and language in another country, it creates conditions for backlash, and for a critical response it may not want.
In the case of Apple — and, to some extent, the NBA — China's market muscle may allow it to prevail. In other cases, such as "South Park" and, perhaps, Xinjiang, it may find shutting people up to be more difficult.
Either way, China's internal and external affairs are now so cross-pollinated that the relatively straightforward territorial pleas of a Zhou Enlai in 1955 — about a dispute that is still playing out all these years later — seem almost quaint in their concreteness.
Addressing the NBA brouhaha, an opinion piece in the English-language version of People's Daily, the Communist Party's flagship newspaper, took up this issue on Thursday.
"What are the social taboos, sensitive issues, and political correctness in China?" writer Ren Yi asked. "They are the integrity of national sovereignty and territory. That is what China values the most."
But in an era of blurred boundaries, of basketball leagues and sarcastic foreign TV shows and apps and tweets and the local becoming the global, the question raised this week isn't going away: Who defines that sovereignty and maps that increasingly virtual territory — China alone, or China along with the world?
Ted Anthony, who covered China for The Associated Press from 2001 to 2004 and oversaw coverage of it as Asia-Pacific news director from 2014 to 2018, has written about global affairs since 1995. Follow him on Twitter at @anthonyted.