China and Taiwan following a well-rehearsed script

'Independence for Taiwan would only bring profound disaster to Taiwan," said China's President Xi Jinping in Beijing on Wednesday, and he ought to know. He is the one who would make sure the disaster happened.

Speaking on the 40th anniversary of US diplomatic recognition of the Chinese People's Republic, Mr Xi said that Taiwan was "sacred territory" for Beijing. He would never tolerate "separatist activities" there: "We make no promise to renounce the use of force and reserve the option of taking all necessary means."

Well now, that would be exciting, wouldn't it? Start with Chinese air and missile strikes on Taiwan, presumably reciprocated by the Taiwanese forces. Probably no nukes, although China does have them, but the first major sea battle since World War II, followed by a Chinese assault landing on Taiwan involving several hundred thousand troops. Quite a lot of death and destruction, in fact.

No? That's not what he meant? Okay, then, what did Mr Xi mean by "all necessary means"? Harsh words and a trade embargo? Then why not say so? Is the Trump thing catching?

There is a peculiar ambiguity to Beijing's official statements on Taiwan. On the one hand, nobody in the Communist regime is in a great rush to gather Taiwan back into the fold. It will happen eventually, they believe, and they can wait.

On the other hand, the regime's credibility (such as it is) comes from only two sources: its nationalist posturing, and its ability to deliver rising living standards. With the latter asset rapidly depreciating -- the Chinese economy is heading south -- the nationalism becomes more important, so a bit of chest-beating is inevitable.

Many people will therefore discount Mr Xi's words as mere rhetoric that the Chinese Communist leader was obliged to use on a significant anniversary, but not a real threat to invade. After all, the deal made 40 years ago pretty much ruled out the use of force.

The US agreed in 1979 that there is only one China, and that it includes Taiwan. There just happened to be two rival Chinese governments at the time: the Communist one in Beijing that won the civil war in 1949 and has controlled mainland China ever since, and the previous Nationalist government that retreated to the island of Taiwan when it lost the war.

Both of these governments agree that there is only one China. In practice, the one in Taipei can never regain control of the mainland, but it claims to be the legitimate government of China, not of Taiwan. Almost everybody else, including the United States, agrees that there is only "one China" and recognises the Communist regime in Beijing as legitimate.

The 1979 deal assumed that this conflict would be resolved peacefully at some unspecified future time, and Beijing made some helpful comments about how Taiwan could enjoy a special status if it reunited with the motherland: democracy, a free press, the rule of law -- the same promises made to Hong Kong when Britain returned it to China in 1997. Then everybody settled down to wait for time to pass and the generations to roll over.

Beijing assumed that the Taiwanese would eventually see the light and rejoin the mainland. The Taiwanese assumed that Communist rule on the mainland would eventually either mellow or just collapse. Either way, we'll all just get on with our lives in the meantime. It was a very sensible, moderate deal -- but those assumptions proved to be wrong.

Communist rule in China has not collapsed, and Mr Xi is the most powerful and authoritarian leader since Mao. Taiwan has not grown resigned to reunion with the 'motherland'; on the contrary, a separatist Taiwanese nationalism has grown stronger with the years. At the moment, in fact, the party in power in Taipei is separatist, though it is careful not to say so explicitly.

It can never happen: China has 1.3 billion people, Taiwan has 23 million. Taiwan's President Tsai Ing-wen takes positions that appeal to the local nationalist/separatists, but she's never going to declare independence. Xi Jinping threatens bloody murder if she declares independence, but he knows that she will never actually do that.

What Mr Xi is really trying to do with his fierce talk is to reinforce the anxiety many Taiwan voters feel about defying China too openly. They don't want reunification, but they do want a quiet life. And his strategy is working: Ms Tsai's party lost badly in the recent local elections, and may be voted out of power in the national elections next year.

It's just a game, most of the time, and each player plays his or her allotted role safe in the knowledge that the script has not changed for decades. The status quo is more secure than it looks. But let just one player deviate from the script, and everybody would suddenly be in a new and very frightening world.

It probably won't happen, but it could.