Pakistan has issued a stark warning to India, declaring that its share of the Indus River is a "red line" and that India cannot unilaterally suspend the Indus Waters Treaty (a landmark 1960 agreement governing how the Indus River system's resources are divided between the two countries). India moved to suspend its participation in the treaty following a militant attack it attributed to groups based in Pakistan, an allegation Islamabad denies. The dispute raises fears of further escalation between the nuclear-armed neighbours, as water access now emerges as a potential new flashpoint alongside longstanding political and military tensions.