Battle lines are hardening along the remote Himalayan frontier that separates China and India, where the two Asian giants have been engaged in a competitive military construction spree, expanding bases and building airfields to accommodate bigger and more heavily armed forces.

A June clash along the countries’ disputed border that left 20 Indian soldiers and an unknown number of Chinese troops dead, according to New Delhi, shows the rising stakes in this high-altitude game of chicken between the two nuclear-armed powers.

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