BEIJING — They offered protection to Deng Xiaoping, a top Chinese leader, as he made a historic trip across the United States in 1979. They were publicly hailed as “patriotic” by China’s public security minister in 1992.

They were courted by a Beijing official to smooth over Hong Kong’s handover from British to Communist Party rule in 1997.

For decades, the “dragon heads” of mafia clans — known as triads — have been widely regarded as muscle-for-hire for those aligned with China’s Communist Party, which has never denied the suspicions and, at times, even offers something of a knowing nod.

That suspected connection is again in the spotlight. Dozens of men, clad in white T-shirts and carrying Chinese flags, chased and beat anti-government protesters and bystanders with clubs in Hong Kong on Sunday, leaving at least 45 people hospitalized and bringing a new element of fear into a polarized city.

In the aftermath, Hong Kong legislators expressed worries that the city’s political crisis was taking a troubling turn with the long-standing criminal syndicates known as triads entering the fray.

The attack sparked outrage from even those who lean toward Beijing.

“Are triads ruling Hong Kong now?” the former head of the pro-Beijing Liberal Party, James Tien, wrote in a Facebook post calling on Hong Kong Chief Executive Carrie Lam to immediately step down.

Experts say there is no evidence showing Sunday’s train station attack was ordered by Chinese officials. But the melee provided a reminder of how the gangs, which grew out of southern China and operate today across several continents, are increasingly aligning themselves with the Beijing government.

Steve Vickers, former head of the Hong Kong police force’s criminal intelligence bureau, noted the train station rampage came hours after demonstrators attacked and defaced the Chinese government representative’s office in Hong Kong, a move that Beijing furiously warned had “touched a bottom line.”

It’s currently impossible to prove the gangsters were motivated to seek revenge for the liaison office attack, “and other interests may have activated’ them,” said Vickers, who runs the Hong Kong-based risk consultancy Steve Vickers and Associates.

“Sunday’s involvement by apparent triad societies represents a most worrying escalation to what is an already highly complex situation,” he said.

'Totally stunned'

On Monday, police announced the arrest of six men, some of whom had triad backgrounds, for the mob-style attacks.

Hong Kong’s police commissioner, Stephen Lo, pushed back against allegations that the force was intentionally slow to respond to the attack on protesters and said his department had been stretched thin.

In a short statement, Lam denounced violence from all sides. In Washington, President Trump said he believed Chinese leader Xi Jinping had handled the Hong Kong unrest “very responsibly.”

Lo Kin-hei, vice-chairman of the opposition Democratic Party and an elected district representative, said his party members had gotten word that a suspected mob attack would take place late Sunday. Local residents received vague warnings on social media to stay home a few hours before the assault began, he said.

Around 9:30 p.m. Sunday, smartphone video showed dozens of men storming into the train station, indiscriminately charging anti-government protesters in black T-shirts and bystanders with no apparent allegiances.

They beat victims cowering on the ground, cornered them inside subway cars and left the Yuen Long station floor smeared with blood. 

“Even though there were triad attacks in the past, they were targeting protesters who spoke out against their masters,” Lo Kin-hei said. “This time it was an attack against anyone, everyone on the platform, on the train. Hong Kong is stunned, totally stunned.”

Junius Ho, a staunch pro-Beijing legislator who was filmed congratulating the white-clad gang during Sunday’s station attack, told reporters Monday that he was thanking the men for “defending their homes.”

He denied that he had ties to criminal elements but refused to apologize for shaking hands with what he characterized as ordinary constituents — some of whom happened to be masked and armed.

“My job is to reach out,” Ho said. He did not respond to a message seeking further comment.

Local politicians and scholars say there is a decades-old but not widely known history of Hong Kong’s criminal underworld embracing the pro-Beijing establishment.

In 1984, Deng was fixated on the strategy of how to reabsorb Hong Kong from the British. He remarked that the triads wielded disproportionate influence and had “many good people.”

A decade later, Tao Siju, China’s top security official, praised Hong Kong triads for offering Deng protection on foreign trips and told the city’s newspapers that triads “also love their country.” 

As Hong Kong transitioned to British rule, a former top official with China’s official Xinhua News Agency, who acted as a liaison for the Chinese government, explained how he wooed the triads on Beijing’s behalf. The argument was financial.

“I told them that if they did not disrupt Hong Kong’s stability, we would not stop them from making money,” Wong Man-fong said to a stunned university audience in 1997. 

Over the past decade, prominent Hong Kong media personalities, all Beijing critics, have been attacked. In 2014, after young anti-government demonstrators seized Hong Kong’s streets during the “Umbrella Movement,” alleged triad members raided their encampment and cleared occupiers.

'Rent-a-mob'

It was a scene familiar in other parts of the worldwide Chinese diaspora, where local leaders sometimes have been open about their “patriotism.”

As anti-Chinese government protests rocked the torch relay before the 2008 Beijing Olympics, one Chinese student leader in Canberra told the Sydney Morning Herald he was not concerned about dissidents marring the Australian leg because local triads already had “quietened them down.”

In 2015, after anti-China protesters occupied the Taiwanese legislature, they were roughed up and dispersed by a gang led by Chang An-lo, the notorious founder of the Bamboo Union triad who went by the nom de guerre “White Wolf.” 

After doing a stint in U.S. federal prison for heroin trafficking and racketeering, Chang returned to Taiwan in 2013 to form a political group promoting political unification with mainland China. Taiwanese police have probed the group’s ties with organized crime.

“There’s a proven link between the Bamboo Union triad and activities on behalf of the Chinese Communist Party,” said J. Michael Cole, a senior fellow at the Global Taiwan Institute. “What we saw in Hong Kong this week is a logical escalation of what we’ve seen for the past decade.”

Chinese state television repeatedly aired video of the defaced government office, blaming what it called U.S. instigation in the Hong Kong protests. Rhetoric on mainland Chinese social media also hardened. “Guard and protect Hong Kong” became the top trending hashtag.

Alvin Y.H. Cheung, a scholar at the U.S.-Asia Law Institute at New York University, said there has been concern for years about triad influence in Hong Kong politics. But the events of this week’s suggested something new.

“Triad members operating in the open and beating up civilians — that is relatively new,” he said. “It’s the same rent-a-mob playbook you’ve seen in other authoritarian jurisdictions.”