High in the Himalayas in a region so rugged and remote even army patrols are normally infrequent, Indian and Chinese soldiers now stare each other down. Armed, angry and threatening war over a gravel road.

The shouting started when China literally bulldozed its way into a disputed border zone, extending a road running through Tibet onto a plateau that overlooks India.

The Doka La area of the Doklam plateau marks a three-way boundary for China, India and the tiny mountain kingdom of Bhutan. But the exact borders are obscured by more than a century of vague agreements and fiery disagreements over who owns what.

Both Bhutan and China claim this particular patch of mountain, based on contradictory descriptions in a treaty from 1890.

India considers it strategically vital. It overlooks the narrow pass that connects the bulk of the country to India's eight eastern provinces, the so-called "chicken neck" it fears could be severed in a potential Chinese assault.

Doka La plateau

When Bhutan found Chinese construction workers in the area last month, it notified its close ally India. Indian soldiers and equipment were dispatched to block the road. Beijing sent several thousand troops, and so did New Delhi to face off barely 150 metres apart. One shoving match was caught on video.

"India should not push its luck and cling to any fantasies" about which side has military superiority, a spokesman for China's Defence Ministry said last week.

Nobody is backing down because the dispute is about much more than the road.

Huge ambitions

It's about two regional giants with huge ambitions and armies to match. Both countries have defiant leaders — Indian Prime Minister Narendra Modi and Chinese President Xi Jinping — eager to fill the void in Asia left by a waning U.S. presence.

"Quite clearly, these two states, which claim friendship, are always going to be incipient rivals," says Elliott Tepper, a former professor at Carleton University in Ottawa and an expert in Asian studies.

"China is pressing its advantages in many directions and one of those directions is in Bhutan."

Beijing has been sending its military to stake claims wherever it feels it has any historical justification, especially the South China Sea. There, it's been dredging to turn small sandbars into islands big enough for military landing strips and missile launch pads.

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Chinese President Xi Jinping, right, walks with Indian Prime Minister Narendra Modi, second from left, during his visit to the Sabarmati river front in the western Indian city of Ahmedabad in 2014. (Reuters)

Many other Southeast Asian countries have complained that this ignores their competing claims and an International Court of Arbitration in the Hague ruled last year that China has no right to the islands it occupies. But that's been ignored by Beijing and the construction has continued.

On Sunday, in a big display of military might, Xi inspected a parade of China's army units and their newest weaponry in Inner Mongolia.

Xi did not mention the border conflict specifically, but he did vow China would stop "invaders." China has "the confidence and capability to defeat all armies that dare to offend," Xi said.

China's also been criss-crossing the region with new land and sea trade routes to try to expand its economic influence under a so-called "One Belt One Road" initiative. That's Beijing's master plan for economic development involving trade deals and infrastructure projects with partners around the world.

Neither India nor Bhutan has bought into that project.

In fact, India has denounced it as nothing more than a power play by China, designed to trick other countries into giving up their sovereignty and becoming dependent on Beijing. Modi stayed away from a showcase summit called by Xi to launch the "One Belt One Road" project this spring, leaving Beijing officials fuming.

"India has been concerned that this plan is just a way for China to encircle or contain it," says Zhao Hai, a researcher with the National Strategy Institute at Beijing's Tsinghua University.

Rising patriotism

But China's tough talk in the border dispute is also being driven by something else: a rising sense of patriotism and power at home, Zhao says.

"There's growing nationalism in China and growing confidence in Chinese military forces, a feeling that national sovereignty will be defended and if war broke out that China's military can definitely win the war."

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A liquefied petroleum gas delivery truck drives along India's Tezpur-Tawang highway, which runs to the Chinese border, in the northeastern Indian state of Arunachal Pradesh in 2012. (Frank Jack Daniel/Reuters)

Indeed, the Beijing tabloid Global Times, which sometimes reflects official thinking, threatened New Delhi with exactly that: "a military confrontation" that would "resolve the conflict through non-diplomatic means."

China's People's Liberation Army would not withdraw, said the editorial page, and there could only be talks once Indian soldiers backed down. That is Beijing's official position.

War has broken out once before between India and China over a border dispute in the Himalayas, and it was also sparked by Chinese construction of a road.

That was in 1962. After a month of fighting, hundreds of soldiers were dead. India was soundly defeated and China was in control of a significant piece of Indian territory. It later withdrew.

Caught in the middle

Of course, much has changed since then. Both countries are much stronger militarily, in possession of nuclear weapons and much more confident. If war were to break out, the risks and stakes would be that much higher.

Other things have not changed much.

The dispute between India and China along a border that stretches for some 3,400 mountainous kilometres seems no closer to being resolved, despite many more rounds of negotiations. Bhutan is often still caught in the middle.

'For both sides it's about face. How to save face.'  -  Zhao Hai

And the outbreak of war is still just one confrontation away, as it remains with the current standoff at Doka La.

Tsinghua University's Zhao says a negotiated settlement can only happen if both countries walk away with one crucial element.

"For both sides it's about face. How to save face," he says.

Because the alternative to backing down gracefully is war. And that would be "disastrous," Zhao says. "There would be no winner, because both sides would end up in a crisis that's hard to imagine."