What this campaign was
Launched in September 2025 after Russian drones and aircraft violated the airspace of seven Allies, Eastern Sentry assembles national contributions along the whole flank — fighters, surveillance aircraft, air defence and frigates. NATO built it on the Baltic Sentry experience.
Eastern Sentry is the only mechanism in the module that spans all of its arenas at once, and it is the clearest example of how the Alliance now responds: with a named, flexible activity layered on standing missions and assembled from national contributions, rather than with a new permanent structure. What it buys is responsiveness; what it does not buy is permanence, and that trade is the open question the module carries forward.
Confidence: High As of 2026-09Reviewed 2026-09-21
Summary
In September 2025 Russian drones and planes violated the airspace of several NATO Allies, including Estonia, Finland, Latvia, Lithuania, Norway, Poland and Romania; incursions into Polish airspace by drones and into Estonian airspace by fighter jets led to security consultations under Article 4. In response NATO launched Eastern Sentry, which it describes as a flexible, multi-domain activity enhancing vigilance along the entire eastern flank. Allies contribute additional capabilities and assets — more fighter jets, helicopters, transport aircraft, air defence systems, surveillance aircraft and frigates — with their coordination improved through NATO. NATO states that the activity builds on the experience of Baltic Sentry and incorporates innovative technologies and tactics to address new challenges, and that its assets complement NATO Air Policing along the flank.
Stated objectives
What the participants say. Each entry cites where the position was stated; Vigil records that it was made, not that it is true.
To enhance NATO's vigilance along the entire eastern flank, with Allies contributing additional capabilities and assets to the Alliance's strengthened deterrence and defence posture.
NATO's own description of the activity.
Assessed objectives
Vigil's reading, graded. Kept structurally apart from stated positions so an assessment can never be published as someone's declared aim.
Its design answers a specific problem the September incursions exposed: air policing is sized for interception of manned aircraft, and the pressure arriving included uncrewed systems in numbers that a four-month fighter rotation was not built for.
NATO states the activity incorporates innovative technologies and tactics "to address new challenges" without naming them; the reading above is Vigil's and is graded accordingly.
Primary forces
- Allied Command Operations Primary force · Confidence: High · as of 2026-06-17
Supporting & external
- Allied Air Command Supporting force · Confidence: Moderate · as of 2026-06-17
NATO states that Eastern Sentry assets complement NATO Air Policing, which Allied Air Command oversees. It does not state a command relationship for the activity itself, and none is asserted.
Outcome and present status
Running since September 2025 and named on NATO's eastern-flank page of 17 June 2026 as a current activity. It has not replaced any standing mission: NATO describes its assets as complementing air policing, and the module models it alongside rather than above.
Observed adaptations
NATO explicitly frames Eastern Sentry as building on Baltic Sentry, which makes the January 2025 maritime activity the template for the alliance's flank-wide response eight months later: a named activity, multi-domain, assembled from contributions, without a new command.
Political implications
Two Article 4 consultations in one month preceded it, which makes it the visible product of the treaty's consultation mechanism working — and a standing reminder that the mechanism was needed.
Military implications
The activity adds mass and sensor coverage without adding structure. Its capability is whatever Allies have contributed at a given moment, which is also the limit of what can be said about it.
Linked events
Locations
Places this module already publishes as map markers, listed because the campaign is about them. Not an operational area.
What remains unknown
- NATO publishes no contributing Allies, units, numbers, basing or duration for the activity, and none is carried here.
- No command relationship for the activity itself is published — only that its assets complement air policing and that coordination is improved through NATO.
- No review point, end date or success criterion has been published.
Readings the evidence also supports
- The activity can be read as a genuine capability addition, or as a political signal assembled from forces that were largely in the theatre already. NATO's published description supports neither reading over the other, and the absence of a contribution list means the question cannot be settled from public material.
Listed because the record's own assessment is not the only one its sources permit — not as a hedge on the assessment above.
Whether the activity becomes a standing arrangement
NATO's word is flexible. Whether Eastern Sentry ends, folds into air policing or hardens into a permanent posture is the single most consequential open question about the module's current phase.
Whether contributions are published
NATO names capability classes and not Allies, units or numbers. Any published contribution list would be new disclosure.
Watch questions this campaign bears on
Standing analytical questions whose evidence runs through this campaign, each with its latest review. Derived from the Watch object, never restated here.
See the force running this in Explore Interactive: select this record and follow what connects to it.
Assessed as of — 2026-09 Last reviewed — 2026-09-21