Chinese and Indian military reinforcements are building up along their disputed Himalayan border after soldiers there had their worst clash in decades last week.

As tensions threaten to boil over, Indian Defence Minister Rajnath Singh used a visit to Moscow this week to urge Russia – the country’s biggest weapons supplier – to speed up delivery of its powerful S-400 Triumph air defence missile system, according to Indian media reports.

Escalating tensions between China and India over the border dispute had spurred New Delhi to step up its air defences to match Beijing, according to Collin Koh, a Research Fellow from the S. Rajaratnam School of International Studies.