New Delhi: As tension mounted between India and China in the wake of the clashes along the Galwan Valley in Ladakh in which at least 20 Indian soldiers have been killed and Chinese suffered 43 casualties, Prime Minister Narendra Modi spoke tough saying that the sacrifice of Indian soldiers will not go in vain.

In a statement, the Army said on June 16, that 17 “critically injured” Indian troops succumbed to their wounds, in addition to an officer and two soldiers who had died earlier.

Speaking at a meeting with Chief Ministers to discuss measures to tackle the COVID-19 pandemic, Modi said India will give a befitting reply if instigated.

Menwhile, External Affairs Minister S. Jaishankar had a telephonic talk with his Chinese counterpart Wang Yi on the rising border tension.

The troops died “in the line of duty at the stand-off location and exposed to sub-zero temperatures in the high altitude terrain … taking the total that were killed in action to 20”, the statement said.

Indian and Chinese troops have disengaged in the areas where the clashes took place, the statement said, adding that India is firmly committed to “protect the territorial integrity and sovereignty of the nation”.

The incident marks the deadliest clash between the nuclear-armed neighbours in decades.

Tensions flare on a fairly regular basis between the two regional powers over their 3,500-kilometre (2,200-mile) frontier, which has never been properly demarcated.

Thousands of troops from the two nations, backed by armoured trucks and artillery, have been involved in the latest face-off since May in the Ladakh region, bordering Tibet.

Indian officials say Chinese soldiers crossed the boundary at three different points, erecting tents and guard posts and ignoring verbal warnings to leave. That triggered shouting matches, stone-throwing and fistfights.

Army officers and diplomats have held a series of meetings trying to end the impasse, with no breakthrough.

Chinese foreign ministry spokesman Zhao Lijian said Indian troops crossed the border line twice on June 15, “provoking and attacking Chinese personnel, resulting in serious physical confrontation between border forces on the two sides”.

“We again solemnly request that India follows the relevant attitude and restrains its front line troops,” he said. “Do not cross the border, do not provoke trouble, do not take any unilateral action that would complicate the border situation.”

China’s foreign ministry confirmed there had been a “violent physical confrontation” on June 15 in the border area. It made no mention of casualties but India’s foreign ministry said there had been casualties on both sides.

The deaths were the first since a border skirmish in 1975 between the nuclear-armed neighbours – also the world’s two most populous countries – which have been unable to settle the dispute along their lengthy frontier.

“This is extremely, extremely serious, this is going to vitiate whatever dialogue was going on,” former Indian Army commander D S Hooda said.