ISW’s September 19, 2025 update distilled for ComplexDiscovery: Estonia invokes NATO Article 4 after a MiG-31 airspace violation; Europe accelerates counter-drone defenses; Russia posts localized gains near Lyman, the Kostyantynivka–Druzhkivka axis, and eastern Zaporizhia; Ukraine strikes logistics in Kursk; and FPV warfare reshapes civilian risk and battlefield mobility.
