China on Wednesday insisted India withdraw its troops from a disputed plateau in the Himalayan mountains before talks can take place to settle the most protracted standoff in recent years between the nuclear-armed neighbors who fought a brief but bloody frontier war in the area 55 years ago.

India must pull back its troops "as soon as possible" as a precondition to demonstrate "sincerity," foreign ministry spokesman Geng Shuang told reporters at a daily news briefing.

His comments came after weeks of saber-rattling in New Delhi and Beijing, as officials from both sides talk up a potential clash even bloodier than their 1962 war that left thousands dead.

The confrontation could spill over into the G-20 summit in Germany later this week where Chinese President Xi Jinping and his Indian counterpart Narendra Modi are expected to meet at a gathering of leaders from five emerging economies on the sidelines of the main event in Hamburg.

The month-long standoff – and unconfirmed reports of troop buildups on both sides of the border – has also underscored the swiftly deteriorating relations between the two Asian rivals.

China claims about 35,000 square miles in the Indian province of Arunachal Pradesh, referred to informally by some Chinese as "Southern Tibet." India says China is occupying 15,000 square miles of its territory on the Aksai Chin plateau.

More than a dozen rounds of talks have failed to make substantial progress in the dispute, although there have been relatively few confrontations in recent years.

China appeared frustrated that India refused to sign on this year to its continent-wide "One Belt, One Road" infrastructure initiative, which includes a component in Pakistan and a part of Kashmir that is contested by India.

China also complained bitterly when Tibet's spiritual leader, the Dalai Lama, who lives in exile in India, visited Arunachal Pradesh in April, something India said amounted to interference in its internal affairs. Yet India also formally joined the Russian and Chinese-dominated Shanghai Cooperation Organization this year alongside Pakistan.

The latest dispute flared up in June after Chinese teams began building a road on territory also claimed by Bhutan. Although China and Bhutan have spent decades negotiating the precise border without serious incident, the tiny Himalayan kingdom sought help this time from its longtime ally, India, which sent troops onto the plateau to obstruct Chinese workers.

China then retaliated by closing a mountain pass that Indian pilgrims use to reach Mount Kailash, a sacred Hindu and Buddhist site in Tibet.

Since then, videos have emerged of Indian and Chinese soldiers blocking each other with their arms and physically jostling without coming to blows. After Chinese officials said India should learn "historic lessons" from its humiliating defeat in the 1962 war, Indian Defense Minister Arun Jaitley shot back by saying that "India in 2017 is different from India in 1962," in a reference to its improved military strength.

In an editorial headlined "India would bear brunt of new border clash," China's outspoken nationalist tabloid Global Times ramped up the rhetoric Wednesday by saying that China was in no mood to make concessions.

"The Indian military can choose to return to its territory with dignity, or be kicked out of the area by Chinese soldiers," said the paper, which is published by the ruling Communist Party flagship People's Daily.

Meanwhile, the more mainstream China Daily suggested that some in the Indian military were seeking payback for the 1962 war.

"Perhaps its defeat in that war was too humiliating for some in the Indian military and that is why they are talking belligerently this time," it said.

Although the Doklam Plateau is not part of Indian territory, India's Ministry of Externals Affairs has called Chinese actions in the area a move with "serious security implications for India."

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Former Indian ambassador to Beijing C.V. Ranganathan said that Doklam is a strategically important area that can provide access to the vital Siliguri corridor – also known as the "Chicken Neck" – that connects India's northeast with the rest of the country. But he said he was "baffled" as to why the dispute flared up now.

"The fact that this has lasted so long is not a good sign," he said. "India and China's relationship has been on a downward trend recently and this in fact is yet another example."