India's border trouble with China runs into decades but the last time blood was spilled on the Line of Actual Control (LAC), before the latest episode, was 45 years ago when the Chinese ambushed an Assam Rifles patrol in Tulung La.
India had lost four soldiers on October 20, 1975 in Tulung La, the last time bullets were fired on the India-China border though both the countries witnessed bitter stand-offs later at Sumdorong Chu valley in 1987, Depsang in 2013, Chumar in 2014 and Doklam in 2017.
Beteeen 1962 and 1975, the biggest clash between India and China took place in Nathu La pass in 1967 when reports suggest that around 80 Indian soldiers were killed and many more Chinese personnel.
While three soldiers, including a Commanding Officer, were killed in the latest episode in Galwan Valley, the government describes it as a "violent clash" and does not mention opening fire.
New Delhi described the locality where the 1975 incident took place as "well within" its territory only to be rebuffed by Beijing as "sheer reversal of black and white and confusion of right and wrong".
The Ministry of External Affairs had then said that the Chinese had crossed the LAC and ambushed the soldiers while Beijing claimed the Indians entered their territory and did not return despite warnings.
The Indian government maintained that the ambush on the Assam Rifles' patrol in 1975 took place "500 metres south of Tulung" on the border between India and Tibet and "therefore in Indian territory". It said Chinese soldiers "penetrating" Indian territory implied a "change in China's position" on the border question but the Chinese denied this and blamed India for the incident.
The US diplomatic cables quoted an Indian military intelligence officer saying that the Chinese had erected stone walls on the Indian side of Tulung La and from these positions fired several hundred rounds at the Indian patrol.
"Four of the Indians had gone into a leading position while two (the ones who escaped) remained behind. The senior military intelligence officer emphasised that the soldiers on the Indian patrol were from the area and had patrolled that same region many times before," the cable said.
One of the US cables showed that former US Secretary of State and National Security Adviser Henry Kissinger sought details of the October 1975 clash "without approaching the host governments on actual location of October 20 incident". He also wanted to know what ground rules were followed regarding the proximity of LAC by border patrols.
A cable sent from the US mission in India on November 4, 1975 appeared to have doubts about the Chinese account saying it was "highly defensive".
"Given the unsettled situation on the sub-continent, particularly in Bangladesh, both Chinese and Indian authorities have authorised stepped up patrols along the disputed border. The clash may well have ensued when two such patrols unexpectedly encountered each other," it said.
Another cable from China on the same day quoted another October 1974 cable, which spoke about Chinese officials being concerned for long that "some hotheaded person on the PRC (People's Republic of China) might provoke an incident that could lead to renewed Sino-Indian hostilities. It went on to say that this clash suggested that "such concerns and apprehensions are not unwarranted".
According to the United States diplomatic cables, Chinese Foreign Ministry on November 3, 1975 disputed the statement of the MEA spokesperson, who said the incident took place inside Indian territory.
The Chinese had said "sheer reversal of black and white and confusion of right and wrong". In its version of the 1975 incident, they said Indian troops crossed the LAC at 1:30 PM at Tulung Pass on the Eastern Sector and "intruded" into their territory when personnel at the Civilian Checkpost at Chuna in Tibet warned them to withdraw.
Ignoring this, they claimed, Indian soldiers made "continual provocation and even opened fire at the Chinese civilian checkpost personnel, posing a grave threat to the life of the latter. The Chinese civilian checkpost personnel were obliged to fire back in self defence."
The Chinese Foreign Ministry spokesperson had also said they told the Indian side that they could collect the bodies "anytime" and on October 28, collected the bodies, weapons and ammunition and "signed a receipt".
The US cables from the then USSR suggested that the official media carried reports from Delhi on the October 1975 incident and they cited only Indian accounts of the incident "ridiculing alleged Chinese claims that the Indians crossed the line and opened fire first".