Last week on 21 October, India upgraded its ‘technical mission’ in Kabul to a full embassy. This follows the week-long heavy border clashes between Pakistan and Afghanistan after the Pakistanis struck Kabul on 15 October with drones, attempting to kill senior leaders of the Pakistani Taliban who have been using Kabul as a base to launch operations into Pakistan.

Because of the sudden deterioration in relations between Pakistan and Afghanistan, India now has a chance to outflank Pakistan, diplomatically, and build a stronger relationship with the new regime in Kabul.

The relationship between nuclear armed India and nuclear armed Pakistan is one of the greatest geopolitical fault-lines of our time, it should not be ignored. Adding Afghanistan to the mix only increases the tension and raises the stakes.

Thus, how did we get here? And what is this geopolitical triangle, India-Afghanistan-Pakistan, all about?

At the end of the British Raj in 1947 the newly independent state of Pakistan inherited the western frontier that the British Indian Empire had drawn with Afghanistan; the Durand Line frontier established in 1893 between British India and the then Emirate of Afghanistan.

Afghanistan historically had uneasy relations with the newly‑born Pakistan. Indeed Afghanistan was initially the only country to oppose Pakistan’s admission to the United Nations. Afghanistan’s government, whether monarchy or republic, harbored irredentist claims on Pashtun‑dominated borderlands of Pakistan and viewed the Durand Line as an artificial colonial imposition rather than a legitimate border.

At the same time, India cultivated friendly ties with Afghanistan early on. The Kingdom of Afghanistan and the Union of India formally established bilateral relations in January 1950. India, while focused elsewhere, was viewed by Pakistan from the outset as a competitor for influence in Kabul. As one academic write‑up puts it, “Afghanistan is the extended frontline state between the two arch‑rivals India and Pakistan in South Asia.”

Thus from the start of independence, we have the essential triangle:

Pakistan seeks to ensure Afghan alignment to its interests (in part to deny Indian influence), Afghanistan pushes back against Pakistani claims and Indian outreach occurs. This dynamic is mediated by the Durand Line dispute, Pashtun identity politics, and the overlay of India‑Pakistan competition.

BLUF: The post‑1947 architecture set the stage for enduring mistrust between Kabul and Islamabad, and for India’s opportunity to build presence in Afghanistan, thus embedding the triangle in the strategic competition between India and Pakistan.

The Durand Line, drawn in 1893 by British India and the then Emir of Afghanistan (Abdur Rahman Khan), extends approximately 2,640 km between what is now Pakistan and Afghanistan. From Pakistan’s perspective it is the international border: Islamabad argues that, by the principle of uti possidetis juris, the boundary inherited from British India stays in effect. From Afghanistan’s perspective, the line lacks legitimacy because it was imposed under colonial pressure and divides Pashtun tribes and khans across the border; Afghanistan has at various times refused to recognise it.

In practice, the disputed status of the line has had four major consequences:

The Durand Line remains a structural fault‑line in Pakistan‑Afghanistan relations; it is unlikely to be resolved in the short term.

In the late 1970s and through the 1980s, the Soviet‑backed Afghan regime faced a broad insurgency of Muslim guerrillas (the “mujahideen”). Pakistan – particularly through its intelligence agency, the ISI – became a major conduit for U.S. and Saudi support to the Afghan insurgents.

Pakistan’s calculus: by supporting anti‑Soviet Afghan forces, Islamabad could (a) align with the U.S., (b) gain influence inside Afghanistan, and (c) lay a claim to “strategic depth” in case India‑Pakistan tensions escalated.

From India’s viewpoint, Pakistan’s role in Afghanistan was problematic insofar as Islamabad sought to shape Kabul in a way unfriendly to Indian interests (for example, by denying New Delhi transit rights, or limiting Indian projects).