14 AUG 2019: Riot police clashed briefly with pro-democracy protesters at Hong Kong’s airport Tuesday night in a chaotic end to a second day of demonstrations that caused mass cancellations and disruptions at one of the world’s busiest transport hubs. Protesters said they planned to return to the airport early Wednesday.

Calm eventually returned, with most of the protesters leaving the airport hours after officers armed with pepper spray and swinging batons tried to enter the terminal, fighting with demonstrators who barricaded entrances with luggage carts.

The burst of violence also included protesters beating at least two men they suspected of being undercover agents and came the same day Hong Kong’s pro-Beijing leader warned that the demonstrators had pushed events onto a “path of no return,” highlighting the hardening positions on both sides.

Police said they were trying to help ambulance officers reach an injured man whom protesters had cornered and detained for about two hours on suspicion of being an undercover agent from mainland China. Rescuers eventually succeeded in getting him to an ambulance, local broadcaster RTHK reported.

Protesters then detained and beat a second man whom they also suspected of being an undercover agent.

After a brief period when planes were able to take off and land early in the day, authorities were forced to cancel the remaining flights. The airport authority suspended check-in services for departing flights as of 4:30 p.m., with departing flights that had completed the process able to continue to operate.

The airport’s website showed at least 120 cancellations and it advised people not to come to the airport.

More than 200 flights were cancelled Monday and passengers were forced to stay in the city while airlines tried to find other ways to get them to their destinations.

The airport disruptions escalated a summer of demonstrations aimed at what many Hong Kong residents see as an increasing erosion of the freedoms they were promised in 1997 when Communist Party-ruled mainland China took over what had been a British colony.

The central government in Beijing has ominously characterized the current protest movement as something approaching “terrorism” that poses an “existential threat” to citizens.

While Beijing tends to define terrorism broadly, extending it especially to nonviolent movements opposing government policies in minority regions such as Tibet and Xinjiang, its use of the term in relation to Hong Kong raised the prospect of greater violence and the possible suspension of legal rights for those detained.

Hong Kong leader Carrie Lam said the instability, chaos and violence have placed the city on a “path of no return.”

She has rejected calls for dialogue, part of what analysts say is a strategy to wear down the opposition movement through police action while prompting demonstrators to take more violent and extreme actions that will turn the public against them.

At the airport, protesters discussed among themselves whether they should simply block all access to the facility.

Meanwhile, paramilitary police were assembling across the border in the city of Shenzhen for exercises that some saw as a threat to increase force against the mostly young protesters who have turned out by the thousands in the past 10 weeks.

Donald Trump tweeted that US intelligence believes that the Chinese government is moving troops to its border with Hong Kong. He provided no additional details.

While China has yet to threaten using the army – as it did against pro-democracy protesters in Beijing in 1989 – the Shenzhen exercises were a sign of its ability to crush the demonstrations, even at the cost to Hong Kong’s reputation as a safe haven for business and international exchange. Images on the internet showed armoured personnel carriers belonging to the People’s Armed Police driving in a convoy Monday toward the site of the exercises.

The U.N.’s top human rights official condemned violence around the protests and urged both sides to settle their dispute through “open and inclusive dialogue.”

The early protests were in neighbourhoods near government offices. However, the airport protest has had a direct impact on business travel and tourism.

Hong Kong has long prided itself as being Asia’s leading business city with convenient regional air links, but analysts warn the impact of prolonged protests and violence could make foreign investors think twice.