1. While writing History of Corps of Signals Volume IV (1973-2000) we have been depending upon inputs sent by units/formations of our Corps as well as memoirs of personnel involved in various operations/events.
2. The inputs received from units/formations are generally sketchy. Neither much have been received from Signals veterans.
3. I am enclosing the first draft of the incidence at Sumdarong Chu. Col OP Mehta (Retd) who provided his experience of CO, 5 Mtn Div Sig Regt during the incidence is the father of present CSO, HQ 4 Corps Brig MK Mehta.
4. I requested the veterans for sharing their experiences so that the Signals portion of the incidence can be enriched.
Maj Gen PK Mallick, VSM (Retd)
Chairman, Corps History Cell
Sumdorong Chu Incidence
Sumdorong Chu is a rivulet flowing north-south in the Thag La triangle, bounded by Bhutan in the west and the Thag La ridge to the north. By the summer of 1984 India had established an observation post on the bank of Sumdorong Chu. This post was manned by personnel of the Special Security Bureau (SSB) through the summer and vacated in the winter. In June of 1986, when a patrol from the 12th Assam Regiment returned to the area, it found a sizable number of Chinese already present, engaged in constructing permanent structures.
On June 26, 1986, the Government of India lodged a formal protest with Beijing against intrusions in this region by Chinese troops, that had occurred beginning on June 16. Beijing denied any such intrusions and maintained that its troops were in a location north of the McMahon Line while the official Indian stance was that the Chinese troops had intruded south of the McMahon Line. The actual region of the incursion has been described as the Thandrong pasture on the banks of the Sumdorong Chu and also as the Wangdung region - which comes under the Zimithang circle of Tawang district . This region falls along a traditional route from Lhasa to Tawang - and from there to the Brahmaputra valley - and the nearby Thag La ridge had witnessed serious clashes in the '62 conflict. [Gautam Das, China-Tibet-India : The 1962 War And The Strategic Military Future, Har Anand Publications, 2009, PP 216-217]
Figure 1. Terrain of the incidence involving Sumdorong Chu
Initial reports put the number of Chinese at 40 - some of them armed and in uniform - who were soon reinforced to a total strength of about 200 men. Statements by Indian ministers in the Parliament described the intrusion as being between 1-2 km deep as the crow flies, supplied by mules along a 7 km trail. By August the Chinese had constructed a helipad and began supplying their troops by air. Regarding the Chinese presence as a fait accompli and to prevent further 'nibbling', the Indian Army began aggressive patrolling across Arunachal Pradesh at other vulnerable areas. In September ’86 – while under pressure from both the public and opposition MPs to adopt a strong posture - the Government of India sought a way out of the crisis by suggesting that if the Chinese withdrew in the coming winter, India would not re-occupy the area in the following summer. This offer was rejected by China whose troops were by now prepared to stay through the winter. By September-October, an entire Indian Army brigade of the 5th Mountain Division was airlifted to Zimithang, a helipad very close to the Sumdorong Chu valley. Referred to as Operation Falcon, this involved the occupation of ridges overlooking the Sumdorong Chu valley, including Langrola and the Hathung La ridge across the Namka Chu rivulet. (These ridges are to the south of Thag La.)
By this time, after decades of intensive re-arming and expansion, the Indian army was very different from the weakly-armed, ill-clothed force that had been painfully mustered in 1962 to drive the PLA out of their commanding positions on Thagla Ridge. Not only were the Indian troops now well prepared and armed for warfare in this terrain, road-heads had been brought nearer the key frontier areas, and plenty of transport aircraft and combat helicopters were available to provide supply and ground-attack support. Troop reinforcements on the Indian side – which had begun with Operation Falcon in late 1986 – continued through early ’87 under a massive air-land exercise. Titled Exercise Chequerboard, it involved several divisions of the Army and several squadrons of the IAF and redeployment of troops at several places in the North-East. The Indian Army moved 3 divisions to positions around Wangdung, where they were supplied and maintained solely by air. Ground support and fighter-bomber aircraft of the Indian Air Force (IAF) were brought in to airfields in Assam and North Bengal. Chief of the Army Staff General K Sundarji’s calculation was that if the Chinese were drawn to respond as they had done in 1962 and used lightly armed infantry to launch fast-moving, hard-hitting sweeps up to and around Indian positions, they could be stopped, surrounded and wiped out by superior Indian forces striking from prepared defensive bases – a tactic Gen Sundarjee called “encirclement/annihilation”. His strategy called also for limited counter-offensives into Tibet if the Chinese reacted in force, with the IAF in an infantry-support role, extending, if necessary to ensure control of the air, to raids on Chinese air force bases in Tibet. Sundarji’s battle scenario seems to have taken Viet Nam’s successful resistance to China’s invasion as exemplary : not long before he had led an Indian military delegation to Hanoi.
Figure 2 : Map of the incidence
The Chinese heavily reinforced in Tibet, inducting field forces from Chengdu and Lanzhou, with fighter bombers and combat helicopters suited to operations at high altitudes. China – which has always had a large military presence in Tibet since its occupation – was said to have moved in 20,000 troops from the "53rd Army Corps in Chengdu and the 13th Army in Lanzhou" by early 1987 along with heavy artillery and helicopters. By early April, it had moved 8 divisions to eastern Tibet as a prelude to possible belligerent action. [ The Sumdorong Chu Incident, https://www.bharat-rakshak.com/ARMY/history/siachen/286-Sumdorong-Incident.html ]
The leadership in Beijing took no risks. There were unconfirmed reports at the time that the Indian army planned and prepared a divisional attack to clear the Chinese out of the Sumdurong Chu area; but twice, according to those reports, last-minute orders called off the attack. [ Neville Maxwell, China's Borders: Settlements and Conflicts, Cambridge scholars Publishing, 2014, PP 95 - 97 ]
What were the lessons learnt?
For China, it appears the standoff diverted the focus of attention from Aksai-chin to the Eastern sector, linking the two to any future solution of the border dispute. China also realized the futility of conflict with a determined, well prepared and well-equipped Indian Army. According to Keshav Mishra, "Overt display of military power had effectively neutralised any adventurist step" by China. Moreover, it was China that extended the ‘olive branch’ inviting Rajiv Gandhi to visit China in a bid to normalise the relations. In retrospect, the firm will of the GOI may have been instrumental in shaping China’s strategy of ‘a face saving pull out’ from Somdurong Chu.
For India, it was a wakeup call. The Government of India immediately shifted focus on infrastructure development, logistic management, redeployment of additional resources and construction of airfields and advanced landing grounds in the North East, changing its policy of years of neglect of the erstwhile North East Frontier Agency (NEFA). As a beginning, India voted for statehood for NEFA and the new state of Arunachal Pradesh was created in December 1986. [Mandip Singh , Lessons from Somdurong Chu Incident, April 26, 2013, IDSA COMMENT, Available at : http://www.idsa.in/idsacomments/CurrentChineseincursionLessonsfromSomdurongChuIncident_msingh_260413 ]
SIGNALS AT SOMDURONG CHU
Lieutenant Colonel O.P. Mehta was Commanding 5 Mountain Divisional Signal Regiment. He was the last Lieutenant Colonel to command the unit before the command was upgraded to Colonel. He has the following to narrate in a discussion with Chairman Corps History Cell on 22 September 2016.
Before taking over Command of 5 Mountain Divisional Signal Regiment, Lieutenant Colonel O.P. Mehta was posted as SO 2 (Communications) at Headquarters 2 Corps. He was handling introduction and use of all the latest communication equipments that were coming in Indian Army. When he went to 5 Mountain Division he found all the communication equipments were of older vintage fit to become museum pieces. All the radio relay equipments were of C41/R222 variety. The state of holding of signals equipment was poor. If the authorisation of multiplexing equipment ACT (1+4), 3A was 20, the unit held only three. Such was the state. He took up a massive effort to backload all obsolete equipments with the help of EME workshops and took up the case for introduction of new equipments. On his request the General Officer Commanding, 5 Mountain Division the then Major General JM Singh of GUARDS wrote a DO letter to General Officer Commanding 4 Corps highlighting the critical requirement of signals equipments. The then SO-in-C Lieutenant General RP Sapra, was an old hand in 5 Mountain Divisional Signal Regiment and ensured all the latest equipments were sent to the unit to make up their deficiencies. Everyday they started receiving 3 Ton full loads of equiments, 100 Kilometers of carrier quad etc.
Since the Division moved up to its operational location with formation and units of two division plus it was a herculean task to provide communications to all with the limited resources of one divisional signal regiment. For example the Artillery Brigade had 12 artillery units.
The Commanding Officer had studied in details the 1962 Indo China War, how the second in command of 4 Infantry Divisional Signal Regiment went in a chopper to find out what went wrong with the communications and got killed when the helicopter was brought down by the Chinese, how the commanding officer went to check the communications and become prisoner of war. He vowed that 1962 will never be repeated, there will never be a failure of communication failure for command elements.
He went about the task methodically. A grid of carrier quad network was made to each brigade headquarters from divisional headquarters. This was duplicated by two lines of JWD-1 cable. The third tier of communications was made by radio relay communications. Another layer was provided by VHF with appropriated sighting of relay/anchor stations. All these were backed up by HF network.
The Corps Commander Lieutenant General NS Narahari was very happy with the communication provided by the unit and commended the unit.
The baloon ultimately did not go up. The preparation was completed. But the unit gained tremendous confidence. They believed, yes, we can do it. Credit goes to the officers, JCOs and men of 5 Mountain Divisional Signal Regiment.