Namgyal Durbuk knows the steep mountainous terrain of Ladakh like the back of his hand. But in the 45 years he has lived here, along the Indian state’s volatile and poorly defined border with neighbouring China, he has watched Indian land disappear before his eyes.

“The Indian government is lying that there is no land capture by China,” said Durbuk, a former councillor. “Our vast green pastures, where local herders used take their cattle, have been taken over. A number of locals have been forced by this situation to sell their cattle and move towards urban settlements for their livelihood.”

The fighting that broke out between Indian and Chinese troops on the Himalayan border last month was the worst assault between the two nuclear-armed nations since 1967. Hand-to hand combat between the two sides with rocks and spiked clubs, at an altitude of around 14,000ft (4,250m) in the inhospitable Galwan valley, saw 20 Indian soldiers and an unknown number of Chinese troops killed. It heightened tensions escalating since early May when China moved thousands of troops and artillery to disputed areas, including the strategic Galwan Valley.

On Friday, the Indian prime minister, Narendra Modi, made a surprise visit to a military post in Ladakh, in what many took as a clear message to China. Since the attack, Chinese and Indian military commanders have met multiple times for disengagement talks, but they appear to have reached a stalemate.

China and India have continued to accuse each other, and now both stake a claim to the valley. India condemned China for what it described as a “premeditated attack” on its troops, and Indian ministry of external affairs spokesperson Anurag Srivastava blamed it on China’s “unjustified and untenable claims”. China’s foreign ministry has said that Galwan Valley has “always” been under Chinese sovereignty.

To those living along the poorly demarcated Line of Actual Control (LAC) in Ladakh, a statement by Modi in the aftermath of the attack, that “China did not enter our territory” rang false. They allege Chinese incursions into Galwan and other disputed areas, such Pangong Tso, are just a continuation of the norm.

An exclusive image obtained by the Guardian of Pangong Tso, a freshwater lake on the border where a similar but non-deadly clash occurred between Indian and Chinese forces on 5 May, clearly shows substantial Chinese military structures, including a radar tower, that have been built close to a ridge known as Finger Four in just the last few weeks, despite agreements to disengage.

There are eight ridges around Pangong Tso, known as the eight fingers. Former military commanders and locals say India used to control the whole area, but Chinese troops have gradually moved in and as of two weeks ago it is understood they now control four of the eight fingers. China is said to be building a helipad and other infrastructure around Finger Four, as well as bringing more troops into the territory.

“The villagers are scared by the presence of the Chinese forces. They are so close they can even see their lights in the night for the first time,” said Durbuk, who recently visited the area and fears India will lose entire the Ladakh region in the coming 20 years if the Chinese annexation continues.

Taking out a notebook, Durbuk drew a map to demonstrate the Indian territory lost in Galwan. He pointed out a water handpump installed in 2010 by local authorities for herders, who used to bring their cattle and flocks of Cashmere wool-producing Changra goats to graze on high-altitude pastures near the border.

But these herders have been driven away and their water pump is now accompanied by Chinese military infrastructure. “The area is under Chinese army control and they have constructed roads and built structures there,” said Durbuk.

Sonam Wangchuk, a celebrated Ladakh-based engineer leading a boycott against China, made a similar observation. “As residents we have seen over years how China have been pushing the line, metre by metre. It’s been the cause of huge economic losses. Thousands of local goat herders have lost their pastures, and therefore their income because of it, and have been forced to become menial labourers in the city.”

In February, a group of local councillors gave a written memorandum to Modi, warning him about the capture of vast pasture lands by China.

“We have been raising the issue of Chinese advancement with the government and army for years. The Chinese have been taking over huge patches of land every year,” said Tashi Namgyal, 30, a councillor for the ruling Bharatiya Janata Party (BJP) representing Shyok area, the closest habitation to Galwan valley.

Another BJP councillor, Urgain Chodon, 30, whose village Koyal is situated along the LAC, alleged China has not only been annexing Indian territory but actively building infrastructure. “The Chinese come with their machinery – dumpers, earth movers – and construct roads and then claim later that it is their territory. When the herders would go to the places they were visiting every year, they would find Chinese occupying these areas,” she said.

Indian and Chinese military and diplomatic channels have publicly agreed to continue a policy of disengagement but recent satellite images appear to show a continued build up of Chinese structures on a terrace overlooking the Galwan river, on the the side of the border claimed by India as their territory. India has now deployed missile firing tanks and anti-tank missile systems along the entire 992-mile (1,596km) long border after China brought in armoured vehicles.

Tashi Chhepal, 60, a retired Indian army captain, affirmed that when he was a young officer, Galwan Valley was considered Indian territory and there were no Chinese posts even close to it.

“There were no roads at that time and we would trek for three weeks on horses from Pratappur Nubra north-east to Chumgtas. On the way, we would rest in the Galwan Valley,” said Chhepal. But with Chinese troops at patrolling point 14 in Galwan Valley, he said such a journey would be unthinkable now.