EUROPE AND THE ARCTIC — NATO has rolled out three Sentry missions across Europe and the Arctic since early 2025. The Sentry missions launched over the past 15 months include new capabilities and expand or repackage existing NATO operations, from air policing patrols to regional deployments, under a more urgent framework.

The alliance launched Baltic Sentry in January 2025, following an undersea cable-cutting incident in the Baltic Sea in December 2024. Allied forces deployed warships, aircraft, and naval drones to the Baltic Sea region as part of the mission. In July 2025, an E-3 Sentry surveillance aircraft flew at 30,000 feet over the Baltic Sea and the Russian exclave of Kaliningrad in support of Baltic Sentry.

Finnish authorities seized a vessel suspected of damaging undersea cables in December 2025. The Sentry missions, also known as enhanced vigilance activities, have largely followed incidents of Russian aggression and other warnings.

In early September 2025, about 20 Russian drones violated Polish airspace and triggered an air defense engagement over NATO territory. NATO announced the Eastern Sentry mission two days after the drone incursion. Military forces sent fighter jets, warships, and counter-drone systems to reinforce NATO's Eastern flank, which borders Russia and Belarus, as part of Eastern Sentry.

Drones and jets violated Romanian and Estonian airspace in the months following early September 2025. Soldiers in Poland are training on a new counter-drone system as part of Eastern Sentry. Spanish fighter jets are stationed in Lithuania under Eastern Sentry and scramble to intercept potential airspace threats. Interceptor drones were deployed to Poland and Romania as part of the mission. In November 2025, fighter jets received fuel from a British Voyager tanker aircraft as part of Eastern Sentry.

"We might not get another warning, so now it's time to move from a reactive posture to a proactive posture," said Ed Arnold, senior research fellow for European security at the Royal United Services Institute.

In February 2026, NATO Secretary General Mark Rutte announced the launch of Arctic Sentry, a vigilance mission to increase security in the High North through exercises, patrols, and other activities. NATO artillery forces participated in Cold Response 26, a routine military training exercise in northern Norway that prepares Western soldiers for combat in the High North, in the weeks after the launch. Cold Response 26 was conducted under the Arctic Sentry initiative in 2026. "These operational activities are a way of capitalizing on that," said Vice Adm. Rune Andersen, chief of the Norwegian Joint Headquarters.