With the economy booming, the sun blazing and Covid practically defeated, Taipei City seemed bustling and carefree this weekend. Yet in the skies far above the city, something far more ominousMenacing or threatening. was afoot: 24 Chinese warplanes had entered Taiwan's airspace, including bombers capable of carrying nuclear weaponsA bomb or other weapon that uses nuclear energy to cause a big explosion. .

This is the latest show of force in a campaign of intimidation by China that may signal an imminent invasion. Such a move could provoke retaliation by the USA, sparking the first direct conflict between great powersA "great power" is a country that can exert major influence all over the world. In the decades after the Second World War, for instance, the two great powers were the USA and the Russian-dominated USSR. since World War Two.

Tensions between China and Taiwan have their roots in the Chinese Civil War, which ended in 1949 with the establishment of a communistAn economic system entailing collective ownership of all means of production in contrast with capitalism, which holds that industry and businesses are controlled and run for profit by private owners rather than by the government. government under Mao ZedongA revolutionary leader, also known as Chairman Mao, who ruled China as head of the Communist Party from 1949 until 1976.. The defeated NationalistsThe Nationalists were loyal to the Chinese ruler Chiang Kai-Shek. After being defeated by the communists in the civil war, Chiang remained ruler of Taiwan until his death in 1975. fled Mainland China for the last corner of the country they still held: the island of Taiwan. China has never accepted the legitimacy of this state and every Chinese leader has promised an eventual reunion.

Until recently this seemed more like a remote ambition than an immediate plan. But no more. Alongside aerial harassment, China is sending warships to the coast and mounting 40 million cyber attacksAttacks by hackers (in this case under the direction of the Chinese state) targeting important computer systems such as those of government agencies. each month. On Friday, the Taiwanese government described China as the "arch criminal" of the international order.

And last night China's president warned that relations between Beijing and Taipei were "grim". Xi Jinping has become the most bellicoseAggressive and willing to fight. leader since Mao Zedong, describing the seizure of Taiwan as "inevitable."

China dwarfs Taiwan in strength, with 2.8 million servicemen making up by far the largest military in the world. But Taiwan has powerful allies. Earlier this month, the USA, the UK and Australia formed a defence pact called "Aukus", committing to defend Taiwan. Chinese leaders are furious. The stage is set for a collision that could escalate into all-out war.

Why are seventy-year-old tensions boiling over now? Several factors are at play:

1. Chinese strength: For decades, China has been focused on rapidly growing its economy, which is now 50 times larger than it was in 1978. It is now competing with America to be the wealthiest and most powerful country in the world and feels confident enough to exert its might.

2. Chinese weakness: Now, though, cracks are showing in the "Chinese miracle". The collapse of the giant company EvergrandeThis huge property company owes 5bn and missed a payment deadline on Friday. Some say that if it went bankrupt it could trigger a financial crisis similar to what happened in the USA in 2008. could trigger a crisis. China's increasingly authoritarian leader Xi Jinping may seek to rally the population around him using a strategy beloved of dictators: a show of military strength.

3. Taiwanese independence movements: Since 2016 Taiwan has been governed by a president who wants formal independenceDue to Chinese pressure on countries and companies, Taiwan is still not widely recognised as an independent country. and signed a major trade pact. China sees this as a provocation.

4. The decline of "the West": As demonstrated by the recent withdrawal from Afghanistan, the USA and its allies no longer have the inclination or capacity to dominate world affairs. China - as well as Vladimir PutinRussia's ruler since 2000. He is a strong opponent of the West.'s Russia - is ready to take advantage.

It is a worrying situation. In an apparently unrelated statement yesterday, UN Secretary-General Antonio Guterres warned that humanity is on brink of nuclear annihilation, with the highest threat in 40 years.

The battle lines are drawn, say those warning of World War Three. Ambitious, authoritarian China makes no secret of its hostile intentions and Western powers show no sign of backing down. Once again, some say, the world is sleep walking into a potentially catastrophic showdown.

It's not time to panic, calmer experts counter. Intimidating tactics are one thing, but an actual invasion would be a drastic move for a Chinese government that values stability and economic growth. Even if it did occur, there is no guarantee that America would respond with full force. Don't sound the sirens just yet.