High up in the Himalayas, Indian and Chinese armed forces warily eye each other across a disputed border region that has become the scene of a tense standoff between the two nuclear powers.

The conflict in the remote Galwan Valley that spans their shared border sparked into life Monday with the killing of 20 Indian soldiers, the first reported deaths in 45 years. China has not disclosed whether its forces suffered any casualties, according to a report in its state-run newspaper, the Global Times.

The deaths have drawn the world’s gaze to a region that the two most populous countries have been…