It is a prospect dreaded by many in Hong Kong, but debate is growing in mainland China about whether the central government should end weeks of upheaval in the city by sending in the People’s Liberation Army (PLA).

The PLA has had a presence in Hong Kong since the city’s return to Chinese sovereignty but – unlike in mainland China – memories of the military’s bloody suppression of pro-democracy students and activists in Beijing in 1989 are still strong in the city three decades on.

Still, images of protesters vandalising Beijing’s liaison office in downtown Hong Kong on Sunday have fanned nationalist anger across the mainland, prompting calls for PLA intervention.

Concerns only deepened on Wednesday when defence ministry spokesman Wu Qian commented on the recent clashes and protests in Hong Kong. Without suggesting any action or plans by the PLA, Wu made clear that the Garrison Law, which governs the operations of PLA troops in Hong Kong, already stipulates that the PLA is legally allowed to help the city maintain law and order at the request of Hong Kong’s government.

“We are closely following the developments in Hong Kong, especially the violent attack against the central government’s liaison office by radicals on July 21,” Wu said.

“Some behaviour of the radical protesters is challenging the authority of the central government and the bottom line of ‘one country, two systems’,” he warned, referring to the formula that grants Hong Kong a high degree of autonomy for 50 years. “This is intolerable.”

Both Article 14 and Article 18 of the Basic Law – the city’s mini-constitution – spell out how and under what circumstances the PLA troops in Hong Kong can be used.

While the legality is clear, analysts still believe that given the exorbitant political cost and complexities involved, using the military would remain an unlikely last resort.

Even Hu Xijin, editor-in-chief of China’s nationalist tabloid Global Times, has spoken out against the idea, citing its “huge political cost” and the “severe uncertainty” it might bring to the situation.

“Once the PLA has taken charge of the situation in Hong Kong and quelled the riots, what’s next?” Hu said in a social media post on Monday.

Hu said there were no governance procedures in place that would allow the PLA to operate in Hong Kong and return things to normal. He also warned that any such action would be followed by international condemnation and a severe backlash among the Hong Kong public.

“The [PLA’s] Hong Kong garrison is the symbol of national sovereignty. It is not a fire brigade for law and order in Hong Kong,” he said.

The South China Morning Post reported last week that military force was not an option for mainland leaders working on a strategy to resolve the city’s biggest political crisis in decades.

And in June Major General Chen Daoxiang, commander of the Hong Kong garrison, assured David Helvey, US principal deputy assistant secretary of defence for Indo-Pacific security affairs, that Chinese troops would not interfere in the city’s affairs, according to Reuters.

The comments support analysts’ assessments that deploying the PLA is not a viable solution to Hong Kong’s crisis.

“Will the mobilisation of PLA troops further inflame the situation? There might be people who will resist or even revolt against the PLA, and that may lead to bloodshed,” said Lau Siu-kai, vice-chairman of the Chinese Association of Hong Kong and Macau Studies, a semi-official think tank.

The last time Beijing sent in troops to quell pro-democracy protests was during the Tiananmen Square crackdown on June 4, 1989 – bloodshed that has stained the PLA and the Communist Party to this day, despite decades of efforts to wipe it from public memory.

“Although they don’t like to admit it, they know they made a mistake in the way they used the PLA [in 1989],” said Larry Wortzel, a long-time PLA watcher, who witnessed the crackdown as an assistant military attache at the US embassy in Beijing 30 years ago.

“In subsequent years, when there were major demonstrations, they managed to handle them with either the People’s Armed Police [PAP] or the Public Security Bureau [PSB], or in some cases a combination of both,” said Wortzel, now a senior fellow in Asian security at the American Foreign Policy Council in Washington.

The PAP is a 1.5 million-strong paramilitary police force tasked with maintaining domestic security and order, while the PSB is the country’s police force.

The June 4 crackdown is still widely remembered in Hong Kong, where tens of thousands gather every year on its anniversary for a candlelight vigil in the heart of the city.

“The activities in Hong Kong and the Chinese Communist Party’s conduct there have really had a profound impact on thinking in Taiwan. It has killed any chance with any political party of [supporting] the one country, two systems,” Wortzel said.

“The last thing President Xi Jinping and the Politburo Standing Committee would want to do, if they can avoid it, is to use the PLA [in Hong Kong].”

The situation in Hong Kong is also being closely watched in the West, with many international firms basing regional headquarters in the Asian financial hub, thanks to its capitalist system and rule of law.

Deploying the PLA to Hong Kong would certainly spark an international outcry and draw huge pressure from Western countries, said Liang Yunxiang, an international affairs expert at Peking University.

“Britain, of course, would have the harshest criticism since it governed Hong Kong for a long time and signed treaties with China to ensure Beijing would keep its commitment to one country, two systems,” Liang said.

In the United States, the repercussions could go beyond verbal condemnation to a shift in policy that might fundamentally change Hong Kong’s status as an international financial centre and prompt an exodus of businesses, according to Wortzel.

“Any move to use the Chinese troops will create a furore in the US Congress … They will re-examine the Hong Kong Policy Act very carefully,” he said, referring to the bill passed in 1992 that allows Hong Kong to be treated as a non-sovereign entity distinct from mainland China on trade and economic matters.

“They will simply treat Hong Kong like another Chinese city, which affects export controls and how the financial industry operates.”

Just last month, members of Congress reintroduced the bipartisan Hong Kong Human Rights and Democracy Act. If the legislation is passed, the US could revoke Hong Kong’s special status under American law if Beijing fails to ensure the city has “sufficient autonomy”.

The crisis comes as Beijing’s ties with Washington are already strained by a year-long trade war that has spilled into other areas of bilateral relations.

There is also mounting international pressure on China over issues such as its mass internment and political indoctrination of an estimated million or more members of Muslim minorities in Xinjiang, despite the Chinese government’s repeated denials of ill-treatment of the inmates and attempts to defend its policies.

Chen Daoyin, a Shanghai-based political analyst, said the increasing scrutiny China faced from Western countries – whether in the form of punitive tariffs or restrictions on technology – made it all the more important for China to keep Hong Kong as an open channel to connect with the world.

“If the military was deployed [in Hong Kong], it would mean China was ready to shut its doors completely,” Chen said.

Lau, from the Chinese Association of Hong Kong and Macau Studies, said the PLA should only be deployed as a last resort.

“It would be a huge blow to the principle of ‘letting Hong Kong people govern Hong Kong with a high degree of autonomy’, since it will prove that Hong Kong people are not up to the task of governing themselves,” he said.

Hu, from Global Times, said the PLA troops could be used only if the authorities lost control of the city or an armed rebellion broke out.

Short of that, he said, the central government should let the chaos in Hong Kong run its course and wait for the public mood to flip.

This strategy of sitting it out hinges on the city’s police force holding the line and stopping Hong Kong’s slide into total anarchy.

Wortzel also warned that there were lines protesters should not cross – or risk provoking the use of military force.

“For instance, to this point, demonstrators have not gone up against the PLA garrison or any of its outposts. If they did that, I think it’s possible – actually it is very likely – that there will be a limited mobilised response [to defend the facilities],” he said.

While most analysts said the chance of Beijing resorting to military force was slim, the very idea – ludicrous to even discuss three months ago – has become a popular topic on social media on the mainland, where the discussion is not censored and many commenters support it.

The official media have been careful not to touch the subject but they too have stepped up rhetoric against the protests in Hong Kong.

In a rare move, state-run China Central Television has run commentaries and reports about protests in Hong Kong during its main evening news for five days in a row.

Only the most politically important issues receive such unusual treatment.