<h1>Antitrust enforcement: international cooperation urged to prevent regulatory arbitrage and preserve contestability in digital markets.</h1> Strong antitrust enforcement and international cooperation are central to preserving competitive digital markets by addressing platform gateway power, data control and market access. Capacity building in artificial intelligence, blockchains and algorithms is necessary for authorities to detect anti-competitive conduct. Incorporating sustainability into competition policy can stimulate cleaner innovation while avoiding anti-competitive barriers. BRICS joint documents on Leniency Programmes and the Digital Economy support coordinated cross-border cartel investigations, improved merger control responses, and the use of soft-law tools and market studies to foster pro-competitive environments.