European and UK officials warn of imminent substantial Russian troop build-up and threat of aggression near NATO borders in late 2025.

In late 2025, high-level UK government sources and European leaders have warned that Russia is preparing for a major military threat against Europe and NATO, with concerning troop movements and intelligence reports indicating a build-up of forces near borders. UK Defence Secretary Ben Wallace along with others highlighted the risk of a full-scale invasion, reinforcing that Europe remains vulnerable to Russian aggression despite NATO's efforts. These warnings come amidst broader geopolitical tensions and a reassessment of military readiness across allied states. Intelligence points to coordinated Russian military activities, including increased warplanes and troop deployments on European borders, heightening fears of a destabilizing escalation. European governments are urged to prepare defensively while diplomatic and military responses are being considered to counteract the looming threat.