Open source satellite imagery has captured what appears to be a heliport China is building in close proximity to two new air defence positions that cover sensitive stretches of the disputed border in Doklam and Sikkim sectors.

The imagery, shared by the open source intelligence analyst who uses the name @detresfa on Twitter, shows the suspected heliport under construction at the tri-junction of the borders of India, Bhutan and China, and at a distance of about 100 km from Doka La (Doka pass) and Naku La (Naku pass).

“Suspected PLA heliport infrastructure spotted [as] part of an ongoing investigation near the #Doklam region of the #India #China #Bhutan tri junction, this support unit could sustain all weather & rapid troop deployments in the sector along with improving surveillance operations,” the analyst tweeted.

The suspected heliport is located almost equidistant from the two sites at which the People’s Liberation Army (PLA) is developing surface-to-air missile facilities, according to imagery tweeted earlier by @detresfa. Both the missile facilities are near what have been described as “suspected early warning radar sites” opposite Sikkim state.

In a graphic posted on Twitter, @detresfa said the “steady build-up of support infrastructure by the People’s Liberation Army of China [near] areas with a history of clashes [and] disputed territorial claims demonstrates the long-term Chinese ambitions in these sectors”.

“With the addition of a heliport along with area denial systems within 100 km from Doka La [and] Naku La, China would be able to sustain all weather operations in the disputed areas regardless of the harsh terrain [and] conditions,” according to the graphic.

The new missile facilities are located roughly 50 km from Naku La (Naku pass), where troops from the two countries had clashed on May 9, and Doka La (Doka pass), close to the Doklam plateau that was the scene of a 73-day military standoff between India and China in 2017.

Four Indian and seven Chinese soldiers were injured in the clash at Naku La, the second such reported incident since the current standoff began in early May.

There was no immediate reaction from Indian officials to the reported development of the heliport and the missile sites by the Chinese.

After the end of the Doklam standoff in 2017 following several rounds of negotiations, there were reports the Chinese side hadn’t fully pulled back its troops from the area. There were also reports that Chinese troops had built trenches, fortified positions and infrastructure to support operations by helicopters and aircraft in the area.

Last month, Hindustan Times had first reported that China had officially stated for the first time that it has a boundary dispute with Bhutan in the eastern sector, a development with significant implications for India as the region borders Arunachal Pradesh state, which is also claimed by Beijing.

Earlier this month, @detresfa had used open source satellite imagery to report that China had stepped up work on military infrastructure opposite Lipulekh region in Uttarakhand. The infrastructure included a surface-to-air missile site on the banks of Mansarovar Lake in Tibet.

The imagery showed what appeared to be two sites at which PLA is creating new infrastructure and accommodation. Both are not far from the Kalapani-Lipulekh region that is at the heart of a new border row between India and Nepal.

These developments come against the backdrop of the Indian Army’s acknowledgement on Monday that its troops had pre-empted efforts by PLA to unilaterally change the status quo along the Line of Actual Control (LAC) on the southern bank of Pangong lake in the Ladakh sector.