NEW DELHI: The People’s Liberation Army (PLA) had "probed" Indian positions and defences in the Daulat Beg Oldi (DBO) sector in at least three places before one of its platoons made the 19km deep incursion into the Depsang Bulge area in northern Ladakh to establish the tented camp there on April 15.

Even as Army chief General Bikram Singh once again discussed the continuing military standoff with national security advisor (NSA) Shiv Shankar Menon on Friday, sources said surveillance imagery captured by spy drones shows that PLA troops had made three simultaneous incursions in adjoining areas in the DBO sector in mid-April.

While the other PLA platoons returned to their bases across the line of actual control (LAC), the over 32 Chinese soldiers stayed back in the Depsang Bulge area, in a move which threatens to cut off India’s access to some 750 sq km in northern Ladakh.

The three flag meetings — held on April 18, 23 and 30 — have failed to break the deadlock till now, with China adamant that India dismantle its observation post at Chumar since it can overlook Chinese positions and keep tabs on troop movements there. Rejecting this, India has asked the Chinese troops to withdraw to their pre-April 15 positions.

India has belatedly taken to strengthening its border infrastructure in response to China’s massive build-up of infrastructure all along the 4,057-km LAC over the last 20 years. While China is irritated with India’s re-activation of advanced landing grounds (ALGs) at DBO, Fukche and Nyoma as well as by the aggressive patrolling by Indian soldiers, the Chumar post seems to have become the major bone of contention.

Indian troops had waylaid two Chinese personnel on mules across the Chumar post around last June. Though they were subsequently let off, China had conveyed its displeasure over the incident, holding that the two Chinese nationals were from its revenue department. Beijing since then has been pressing hard for the Chumar post to be dismantled.