TAIPEI, Taiwan — As a junior diplomat posted to Fiji in the 1990s, Chen Yonglin and the rest of his embassy colleagues fixated on the most sensitive issue in all of Chinese diplomacy: Taiwan.

He tracked Taiwan’s pharmaceutical and agricultural aid to the remote Pacific archipelago. He monitored Taiwanese officials’ interactions with the local Chinese community. He tried to dissuade Fijian officials from attending Taiwan’s National Day celebration every October and local hotel managers from hosting it. When that failed, he sat in a coffee shop across the street to observe — discreetly — who attended.

“At most, a braver colleague would wander over and peek inside,” said Chen, who was a third secretary in Fiji from 1994 to 1998 and defected in 2005 while serving in Sydney. “But gate-crash? Never. That was a different time.”

The difference was laid bare this week after Fijian media outlets reported that Chinese officials barged into the annual Taiwanese celebration, sparking a scuffle that left a Taiwanese official hospitalized. The basic contours of the incident were not rebutted by either government, and it was the latest aggressive turn by Chinese diplomats, who are quickly shedding their traditional image as one of China’s more polished, less muscular arms of government.

The behavior of the Chinese diplomats underscores the political pressure inside the bureaucracy to publicly defend China’s position on global issues, particularly over Hong Kong and Taiwan. China’s Communist Party never conquered Taiwan after gaining power in China in 1949 but claims it as part of an “inviolable one China” that must be reunified. Its officials often object to remarks, diplomatic exchanges or events that present Taiwan as a sovereign state.

Chinese officials have also accused the West of supporting violent separatism in Hong Kong, where most protesters have called for Beijing to follow through on a promise to grant it some political autonomy, and a small minority seek outright independence.

On Monday, Chinese Ministry of Foreign Affairs spokesman Zhao Lijian accused Taiwan of displaying its flag at the Oct. 8 party in Suva, the Fijian capital, and serving a cake resembling the red-and-blue flag.

Chinese officials carrying out “official duties” arrived at the public area of the party and found the celebration “attempted to create ‘two Chinas’ or ‘one China, one Taiwan,’ ” Zhao said. One of the Chinese officials were injured after they were first provoked by the Taiwanese, he added, while demanding a local police investigation.

Taiwanese Foreign Minister Joseph Wu condemned China’s “uncivilized wolf warriors,” a term used in China and abroad referring to the new breed of more muscular Chinese diplomacy. “As a sovereign state, we’ll celebrate Taiwan National Day everywhere, every year.”

On Tuesday, Fijian officials said that Chinese and Taiwanese embassy officials had settled the dispute amicably and that the police would drop the matter.

Still, the incident reaffirmed a noticeable shift in recent years as China has grown in strength, while its leader, Xi Jinping, has urged several branches of government, including its diplomats and state media workers, to “tell China’s story well” and be more confident in defending the country’s image overseas.

At a “mobilization and deployment” meeting in November, Qi Yu, a veteran Communist Party official who had no diplomatic experience but was recently installed as the party secretary at the Ministry of Foreign Affairs, called on diplomats to “firmly hit back at those who defame socialism with Chinese characteristics and protect the nation’s political security.”

“Increase your political determination, be brave enough to fight, be able to fight,” he told staffers, according to a published account by the ministry.

But controversies involving state employees are mounting.

Last year, a Chinese state television reporter was reprimanded by a British judge for angrily slapping a volunteer at a political conference where Hong Kong was discussed. The volunteer had asked the reporter to leave after she stood up to angrily denounce panelists as “puppets” and Hong Kong “separatists.”

In 2018, upset Chinese officials sparked a minor incident when they forced their way into the foreign minister’s office in Papua New Guinea to argue over the wording of a communique at an Asia-Pacific Economic Cooperation summit. Police eventually had to be called.

Zhao, the ministry spokesman, is one of the most high-profile adherents to what Chinese media outlets call “wolf warrior diplomacy.” While stationed in Pakistan, he frequently touted China’s reeducation and assimilation campaign in Xinjiang and publicly locked horns with its critics, including former Obama administration official Susan E. Rice. This year, after he transferred to his high-profile position as China’s public face, he infuriated the Trump administration by suggesting the novel coronavirus was brought to China by U.S. soldiers.

Chen, the former diplomat, said there is more pressure on rank-and-file officials than in his day. Pressure to be tough on Taiwan is pronounced for officials serving in the South Pacific islands, which for decades have been a battleground for influence between Beijing and Taipei, he said.

“Before, you reported what information you gathered,” he said. “Now you have to show what ­‘active’ actions you took. If you’re considered passive, that won’t reflect well on your career.”

The pressure on Chinese diplomats also reflects the mounting tensions and anxieties of the current moment in Beijing and the need to be tough toward Taiwan, said Natasha Kassam, a former Australian diplomat in Beijing.

Since the beginning of 2020, China has adopted a far sterner posture toward Taiwan even as it rolled out a tough national security law to rein in Hong Kong.

The People’s Liberation Army has dispatched an unprecedented number of fighter jets near or into Taiwanese airspace to express its displeasure with Taiwan’s growing ties with the United States. Chinese domestic security officials have announced new campaigns to capture Taiwanese spies. State media outlets are showing footage of the PLA practicing an invasion of Taiwan. Military commentators are openly discussing the prospects.

“Taiwan was always sensitive, but the focus has intensified the last few months in a palpable way,” Kassam said. “What happened in Fiji wasn’t so much about Fiji but much more about what’s going on in Beijing.”