India Rejects PCA Supplemental Award on Indus Waters Treaty — Pakistan Hails 'Huge Legal Win'

India's Ministry of External Affairs formally rejected the Permanent Court of Arbitration's May 15, 2026 supplemental award on the Indus Waters Treaty dispute, with MEA spokesperson Randhir Jaiswal declaring the tribunal 'illegally constituted' and its award 'null and void' — a position India reiterated on May 18. The PCA, in The Hague, issued the supplemental procedural ruling unanimously affirming that India could not unilaterally suspend the arbitration proceedings, and that the treaty remains in force regardless of India's April 2025 suspension notice. Pakistan's Foreign Office welcomed the ruling as a 'huge legal win' and a vindication of Pakistan's position that the IWT cannot be suspended over unrelated security disputes. Pakistan's position is that India's weaponisation of water — withholding Indus basin flows affecting agriculture for 200+ million Pakistanis — violates international humanitarian law regardless of any security grievances. India maintains the tribunal was constituted in violation of the treaty's own dispute-resolution procedure, which requires World Bank facilitation, not a unilateral referral to the PCA. The World Bank distanced itself from the proceedings in 2022 after India and Pakistan each initiated separate dispute mechanisms (India in a Neutral Expert process, Pakistan in arbitration). The dispute is the most complex legal dimension of the post-Sindoor bilateral freeze: India's IWT suspension in April 2025 — triggered by the Pahalgam massacre — was the first such suspension in the treaty's 65-year history, and no mechanism exists for its enforcement. The IWT remains technically 'suspended' by India; full diversion of western rivers (Indus, Jhelum, Chenab) is not physically feasible without major new dam construction.