THE rest of the world may gasp in awe at China's surging economy and cower somewhat in face of its growing might, but its own leaders seem far from complacent. Indeed, to judge from its latest defence white paper, and from a continuing crackdown on its critics at home, China's government feels besieged.

The white paper, produced every two years since 1998, with the latest dated 2010, did not appear until March 31st this year. Maybe it was late because the world has been changing too fast, in too many unsettling ways. The paper suggests a world resentful of China's emergence as a global power, and trying to thwart it: “Suspicion about China, interference and countering moves against China from the outside are on the increase.”

The white paper claims “the armed forces resolutely subdue all subversive and sabotage activities by hostile forces.” In fact, that task is being pre-empted by other organs of the Chinese state. They have been conducting the biggest round-up of dissidents, human-rights activists, lawyers and bloggers seen for years.

According to Chinese Human Rights Defenders, an NGO, by April 4th some 30 people had been detained and faced criminal charges relating to the so-called “jasmine revolution”—an inchoate internet campaign to emulate in China recent upheavals in the Middle East and north Africa. Human Rights Watch, another NGO, reports that a further 100-200 people have suffered repressive measures, from police summonses to house arrest. This has been accompanied by tighter censorship of the internet, the ousting of some liberal newspaper editors, and new curbs on foreign reporters in China, some of whom have been roughed up.

Then this week the dragnet pulled in Ai Weiwei, the best-known dissident in China not to be behind bars. A famous artist, with an installation now on display at a gallery in London and a lasting legacy in the “bird's nest” stadium in Beijing built for the 2008 Olympics, Mr Ai is also, as the son of a revolutionary poet, the Communist equivalent of minor royalty. On April 3rd he was detained at Beijing airport as he tried to board a flight to Hong Kong. His companion was told that Mr Ai had “other business”.

He has been in trouble before. Last year he was prevented from travelling abroad to attend the ceremony in Oslo where Liu Xiaobo, a jailed Chinese dissident, was awarded the Nobel peace prize. This January his studio in Shanghai was demolished, in what he saw as an act of retribution for his political activism.

Now the police seem determined to find evidence of some “crime”. Soon after his detention, a dozen officers arrived at his studio. They detained people they found there for questioning, and confiscated computers. Mr Ai's associates fear that his latest troubles are more serious than previous tangles with the authorities, and that the instructions to take action against him have come “from the top”. After the detention, the official press was at first silent about him, until Global Times, a party newspaper, described him as “close to the red line of Chinese law”. Then, in a terse midnight report, the official news agency revealed that he was being investigated for “economic crimes”. It smacked of “Alice In Wonderland”—detention first, suspected crime later.

In the end, Mr Ai's celebrity seems to have afforded him no protection, and may even have rendered his liberty more precarious. The party seems intent on showing that it will allow no leeway to those dreaming of a people-power movement or democracy. The higher-profile the victim, the more forcibly that message is conveyed. Mr Ai seems likely to become the latest victim of the use of the law to impose political orthodoxy. On March 25th Liu Xianbin, an activist, was sentenced to ten years in prison for “slandering the Communist Party”.

Even more worrying, however, is the increasing resort to informal detentions, punishments and disappearances. These are outside the law, offering the victim no protection at all. The government now dismisses the idea that one function of the law is to defend people against the arbitrary exercise of state power. On March 3rd a Chinese foreign-ministry spokeswoman told foreign journalists: “Don't use the law as a shield.” Some people, she said, want to make trouble in China and “for people with these kinds of motives, I think no law can protect them.”

It is tempting to dismiss the current crackdown as just the latest twist in the unending cycle of repression and liberalisation through which China has been spinning for over three decades. Popular uprisings abroad, like sensitive political anniversaries or big events such as the 2008 Beijing Olympics at home, offer pretexts for a round-up of the usual suspects. They provide a stiff but effective reminder that in China's political system—“a people's democratic dictatorship”—it is the dictatorship bit that counts.

This bout of repression, however, may reflect more than the usual cycle. For a start, it is a huge overreaction. For all the online chatter, no one thinks China is on the brink of a jasmine revolution. Also, with a leadership transition coming next year, and China's new rulers mostly already identified, it helps quash any notion that they might usher in an era of liberalisation.

Never taking off

Although the short-term risk of a copycat revolution in China is small, events elsewhere have demonstrated the long-term corrosive effect on repressive regimes of the internet, mobile telephones and social networks. Better, the party seems to have concluded, to crack down long and hard now than to wait and see. In George Orwell's novel “1984”, an intellectual party hack paints a vision of the future as “a boot stamping on a human face—for ever”. China has updated that. Its vision seems to be of a computer screen with a message that the website you seek is unavailable; or perhaps of a mysterious encounter at immigration, and the interpolation of “other business” between check-in and flight.