Tensions in East Asia are certain to escalate later this year, with China's move to crack down on what it views as subversive activity in Hong Kong exacerbating already strained relations with the United States that supports the territory's independence.

Should China take a harsher line against Hong Kong, self-governing Taiwan, which the mainland regards as a renegade province, would be more confrontational with Beijing and get closer to Washington, leading to a further deterioration of their ties.

Over the Hong Kong issue, Japan, one of the closest U.S. allies, may be forced to consider how to get along with China, its neighbor and major trading partner, as the administration of U.S. President Donald Trump is expected to urge it to act in solidarity.

In Hong Kong, the legislative election is scheduled in September. The United States is also slated to hold its presidential election in November.

"Most importantly, Hong Kong developments today must be contextualized against the struggle between the United States and China that has been going on," said Victor Teo, a regional expert at the University of Hong Kong.

"It is likely that the geopolitical situation in East Asia will become really tense this summer and autumn because of the elections in Hong Kong and the United States," he added.

Under the "one country, two systems" framework, Hong Kong was promised it would enjoy the rights and freedoms of a semi-autonomous region for 50 years following the former British colony's return to Chinese rule in 1997.

China has stepped up involvement in Hong Kong, especially since Chinese President Xi Jinping came to power in 2012, fanning fears that Beijing will erode its freedoms and human rights.

In Hong Kong, large-scale demonstrations sparked by a now-withdrawn controversial extradition bill with mainland China morphed into an anti-government movement last year, with protesters calling for a probe into police use of force and more democracy.

At this year's seven-day annual session of the National People's Congress, which ended Thursday, a resolution regarding the introduction of a security law for Hong Kong was passed.

"China is increasingly concerned about Hong Kong being used as a hub to import instability into mainland China," said Stephen Nagy, a senior associate professor at International Christian University in Tokyo.

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Although the Basic Law, the mini-constitution in effect since the handover, stipulates that Hong Kong has to enact an anti-subversive law on its own, an attempt to do so failed in 2003 as 500,000 people took to the streets in protest.

As the legislative process has been suspended ever since, the Communist-led Chinese government has decided to enforce a national security law designed to ban separation, subversion, foreign interference and terrorism in Hong Kong.

"Beijing is taking advantage of the global distraction created by the coronavirus pandemic to impose its will on Hong Kong, in direct violation of its international commitments," Freedom House President Michael Abramowitz said in a statement.

"The Chinese leadership is essentially trying to bypass Hong Kong's legislature to enact a repressive law with profound implications for freedom and human rights in the territory," said the head of the Washington-based nongovernmental watchdog on democracy.

Trump has pledged to take "powerful action" against China, with Washington asking Beijing to respect Hong Kong's high degree of autonomy and civil liberties, which are key to preserving the territory's special trade status under U.S. law.

U.S. Secretary of State Mike Pompeo said Hong Kong could no longer be seen as maintaining a high level of autonomy from China and that the territory will not warrant special trade treatment under U.S. laws.

China, however, has lambasted the United States for interfering in Hong Kong. Foreign Ministry spokesman Zhao Lijian said Hong Kong is "purely China's internal affairs," and Beijing will take measures to "counteract wrong actions by external forces."

Malcolm Cook, a visiting senior fellow at the Singapore-based ISEAS-Yusof Ishak Institute, said, "In 2014, Beijing and the Hong Kong government successfully waited out the Umbrella Movement that sought to defend Hong Kong's autonomy."

The series of protests were aimed at compelling mainland China to abandon its plan to preselect candidates for Hong Kong's leadership elections.

"This time though that strategy did not work," Cook, who is now staying in Sydney, said, adding, "Beijing thinks that more control over Hong Kong is necessary."

Teo said confusion in the territory has directly influenced Sino-U.S. relations, as it is "no secret that the United States has been supporting young students in Hong Kong to fight against Beijing and to promote Hong Kong independence."

"In order to put a stop to this, as well as to protect Hong Kong from being used in this struggle, Beijing has therefore decided to step in and promulgate the law," Teo said.

Tai Wan-chin, a professor emeritus at Tamkang University in New Taipei City, said the enactment of the national security law in Hong Kong would affect Taiwan, which Beijing claims it has governed under the one country, two systems principle.

China legislating the law for Hong Kong will "to a certain extent increase doubts among some Taiwanese people about Beijing's assurance of the one country, two systems" policy, originally formulated by the mainland to unify with the democratic island, Tai said.

Taiwan and mainland China have been ruled separately after they split in the wake of a civil war in 1949. Beijing has since endeavored to undermine Taipei's quest for international recognition, but the Trump administration has forged close ties with Taiwan.

The Taiwan Relations Act was passed by the U.S. Congress in 1979 after the United States switched its diplomatic recognition from Taipei to Beijing.

Under the act, the United States maintains substantive though unofficial ties with Taiwan and supplies the island with arms and spare parts to enable it to sustain sufficient self-defense capabilities.

Teo warned that Taiwan, in tandem with the United States, "might see an opportunity to do something more drastic," which would rattle the security environment in East Asia down the road.

Beijing, meanwhile, is set to "reach out to critical U.S. allies in the region" such as Japan to try to ensure that the United States and others "cannot exert collective pressure on China," Nagy said.

Recently, the governments of the world's second- and third-biggest economies have improved their relations by effectively shelving bilateral disputes, including a territorial spat in the East China Sea. In contrast, Beijing's ties with Washington have worsened.

"For Tokyo, China will continue to preach the virtues of deepening trade relations with Japan and continue to offer favorable conditions to Japanese businesses in the mainland," but Prime Minister Shinzo Abe will "engage Beijing cautiously," Nagy said.

Japan is "clear-eyed that the turn towards hard digital authoritarianism is here to stay and that Beijing is bent on reshaping the region such that it is in a dominant position," he said.

"If this is successful, it would come at Tokyo's expense, and as such, there is little appetite to weaken the Japan-U.S. partnership," Nagy added.

(Mina Kotani in Tokyo contributed to this story.)