What this campaign was
Launched on 12 September 2025, in a month when Russian drones and aircraft entered seven Allies' airspace, Eastern Sentry assembled national fighters, surveillance aircraft, air defence and frigates along the whole flank. NATO now says its assets are integrated into the 2026 air defence posture.
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 2026-10Reviewed 2026-10-01
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. SACEUR ordered it on 12 September 2025 under his existing authorities, and said it would integrate air and ground-based defences and field counter-drone sensors and weapons with Allied Command Transformation. In 2026 Allied Air Command describes itself as leading the activity, with missions controlled from the air operations centre at Uedem, and NATO ran counter-drone trials under it in Romania in April and over the Baltic states in May. NATO's own pages of 29 September 2026 say that Eastern Sentry enhanced Air Policing and served as a bridging mechanism towards a more robust air defence posture, and that the additional assets first deployed under it have been integrated into NATO Air Defence along the eastern flank. NATO has not announced an end to the activity.
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 2026-06-04
Allied Air Command's own 2026 releases say it leads the activity and coordinates its multi-domain capabilities under a single command structure; they were read through a mirror, because the command's site refuses tools, and SACEUR's order of 12 September 2025 remains the published basis. The role stays graded as supporting until a NATO page read directly says more.
- Combined Air Operations Centre Uedem Supporting force · Confidence: Moderate · as of 2026-05-29
Allied Air Command states that the centre at Uedem coordinated and oversaw the counter-drone training flown over Lithuania and Latvia under Eastern Sentry on 27 May 2026. Read through a mirror.
Outcome and present status
Launched on 12 September 2025. In 2026 NATO folded what it built into the air defence posture that replaced Baltic Air Policing: NATO's pages of 29 September 2026 call Eastern Sentry a bridging mechanism and say its additional assets have been integrated into NATO Air Defence along the flank, while the eastern-flank page of the same date still describes it in the present tense. No end has been announced, and the record stays open.
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 consolidated list of contributing Allies, units, numbers, basing or duration for the activity. Contributing states have announced their own — Danish fighters and a frigate, French Rafales in Poland, German Eurofighters, British Typhoons, Czech helicopters — and some of those were time-limited; no aggregate is carried here.
- SACEUR ordered the activity under his existing authorities, and Allied Air Command says it leads it in 2026. No new headquarters or standing force was created, and no source states which national assets were placed under NATO command for it.
- No review point, end date or success criterion has been published.
- The two Article 4 consultations are recorded from NATO's statement and from the requesting governments' own announcements; the consultations' content is not published by either, and nothing here characterises it.
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 is formally closed into the air defence posture
NATO now describes Eastern Sentry as the bridge to NATO Air Defence and its assets as integrated into it. A published end of the activity, or its continued separate tasking, would settle which it is.
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 — 2026-10 Last reviewed — 2026-10-01