THE music is upbeat but martial, like the score of a Hollywood blockbuster about an alien invasion.

China’s People’s Daily, the main mouthpiece of the Communist regime, has laid the track down over moving images of a column of armoured cars and gringo green military trucks rolling, in close formation, along a new highway, the road to Hong Kong.

This imagery, this crude show of power to protesters in the former British colony, might evoke old school propaganda.

But its delivery was fresh, on the social media platform Weibo, Beijing’s answer to Facebook, Twitter or Instagram.

And its message was clear too, at least for those worried about tensions in Hong Kong.

The PLA, China’s People’s Liberation Army, the video is suggesting, is not far away. The armoured cars and trucks, after all, were in Shenzhen, the city that borders Kowloon.

China already has a garrison in Hong Kong. It has done so ever since the British flag was lowered over the territory in 1997 and China, through local proxies, took power, albeit maintaining a different legal and political regime to that of Communist mainland.

So why the video?

Well, its publication, according to Dixon Sing Ming, a political-science professor at the Hong Kong University of Science and Technology, was “psychological warfare tactic”.

“The drill is part and parcel of

a well-coordinated attempt by Beijing to pressure the protesters and the public to give up their five demands, including the one for universal suffrage immediately,” Mr Sing told Hong Kong’s English-language daily, the South China Morning Post.

Hongkongers do not need to be reminded the PLA has form putting down pro-democracy protesters.

It is 30 years since Communist hardliners used the army to put down the Tiananmen Square protests in Beijing.

So far, mass protesters in Hong Kong have only come into conflict with local riot police (though a video of an officer calling his colleagues “comrades” in Mandarin rather than the Cantonese spoken in Hong Kong has gone viral).

Local police are accountable to authorities in the Hong Kong Special Administrative Region rather than, directly, to Beijing.

They have clashed with protesters, some of whom believe they are already under attack by mainland security agents.

That provoked some of the ugliest scenes yet – at Hong Airport this week.

Police said they tried to help ambulance officers reach an injured man that protesters had detained on suspicion of being an undercover agent.

Demonstrators also detained a second man they suspected of being an undercover agent.

After emptying out his belongings, they found a blue T-shirt that has been worn by pro-Beijing supporters, which they said was evidence he was a spy.

The protests began last month because of widespread opposition to a now-shelved extradition bill, but activists have since expanded to demands for full democracy and police accountability.

This week they have targeted the airport, stopping all flights in and out for two days.

Flights resumed yesterday, but as months of tensions start to boil over, China watchers are starting to ask horrible questions.

What happens if troubles escalate? Are, they whisper, Hong Kong police ready to kill for China?

Or, if things get really bad, will those from the mainland be brought in to do the dirty work?

Minxin Pei, a professor at Claremont McKenna College in California, stressed such a move would effectively end the constitutional compromise under which Hong Kong was handed over to China.

Writing in the South China Morning Post, he said: “Hong Kong’s 31,000-strong police force is not up to the task of carrying out such a crackdown.

“Not only does it lack the manpower; its officers may refuse to use deadly force.

“After all, there is a big difference between firing rubber bullets at a crowd and murdering civilians.

“This means China would have to deploy the PLA garrison or transfer tens of thousands of paramilitary soldiers from the mainland.

“Hong Kong’s residents would almost certainly treat Chinese government forces as invaders, and mount the fiercest possible resistance.

“The resulting clashes, which would likely produce high numbers of civilian casualties, would mark the official end of the ‘one country, two systems’ arrangement, with China’s government forced to assert direct and full control over Hong Kong’s administration.”

 

The stakes, then, could not be higher. Hong Kong, with its rule of law and complex financial markets, acts as a sort of capitalist bridge to CommunistChina. If it were to break down, the consequences for all of China would be dire.

The New York Times asked democracy campaigner Martin Lee what he thought would happen.

He could not say. “We are at a crossroads,” he told the paper. “The future of Hong Kong – the future of democracy – depends on what’s going to happen in the next few months.

Modern Hong Kong, at its heart, is a compromise by its very nature.

But can its leaders, local and Beijing, compromise to preserve it?