The Kursk Incursion, Opening Phase (August 2024): How Surprise Was Achieved and Where It Ran Out

2026-10-13 · 2024-08-06 – 2024-08-21

Overview (BLUF)

Before dawn on 6 August 2024, Ukrainian forces crossed from Sumy Oblast into the Sudzha and Korenevo districts of Russia's Kursk Oblast. Russian forces had received warnings in advance but still failed to respond coherently in the first days. Ukraine claimed control of about 1,000 km² by 12 August, and 1,263 km² and 93 settlements by 21 August; ISW, working from satellite imagery and open sources, estimated about 800 km² over the same period. Ukraine announced control of Sudzha on 15 August.

The phase shows that operational surprise is still possible on a "semi-transparent" battlefield if intent and capability are kept ambiguous. Turning the ground gained into political or military advantage, however, required force depth Ukraine did not have. Russia responded without significantly reducing its main effort in the east, and Ukrainian forces withdrew from Sudzha in March 2025.

Elevated view over central Sudzha: a red-roofed cultural centre and square, trees and low-rise buildings, with flat open fields reaching to the horizon — Photo 1. Central Sudzha, photographed before the operation (date unknown). Ukraine announced control of this district town on 15 August — Photo: kkv1970, CC BY-SA 3.0, via Wikimedia Commons (originally from Wikimapia)

Background and Strategic Context

In summer 2024 Russian forces held the initiative in Donetsk Oblast, above all on the Pokrovsk axis, while Ukraine's northern border regions were under sustained glide-bomb and missile attack launched from across the border. On 13 August a Ukrainian Foreign Ministry spokesperson said the aim was not to seize territory but to stop Russian reinforcements reaching the Donbas and to halt cross-border strikes. Poland's OSW assessed on day two that the operation might relieve pressure near Kharkiv but that its main purpose was political: to show that Ukraine could still seize the initiative.

The Russian side matters just as much. Captured documents reported by The Guardian (not independently authenticated) indicate that Russian commanders were warned from January 2024 of a possible border breakthrough, and by mid-June of a specific thrust along the Yunakivka–Sudzha direction aimed at taking Sudzha. A June document also complained that border units averaged only 60–70% of authorized strength and consisted mostly of poorly trained reservists.

Terrain and Weather

Southwestern Kursk Oblast is gently rolling forest-steppe: open fields broken by windbreak tree lines and gullies (balkas). Movement followed the road network — the Sudzha–Kursk and Sudzha–Rylsk roads — and district road junctions such as Korenevo. To the west, the Seim River closes off the Glushkovo district from the north, and Russian sustainment there depended on a handful of bridges (Figure 1). Early August is the dry height of summer, which likely imposed few limits on cross-country movement or drone use (specific weather records for the operation's days were not confirmed).

Forces and Dispositions

Ukraine: OSW estimated a grouping of about 2,000 troops built around one mechanized brigade and one air assault brigade, with artillery and air defence support. The lead echelon was two platoons (about three tanks), growing by the evening of 6 August to some 400 troops, 11 tanks and about 20 armoured vehicles. Further air assault reserves, artillery and drone teams reportedly followed. Electronic warfare personnel moved with small units.
Russia: The border line was held by FSB Border Service troops, Interior Ministry and National Guard (Rosgvardia) units, and conscripts, supported by regular army artillery and aviation. The responsible "North" operational grouping had most of its strength committed in northern Kharkiv Oblast. Early reinforcements included naval infantry brigades moved from southern sectors.

Course of the Action

Schematic map of the opening phase: an entry axis from the Sumy Oblast border to Sudzha, axes from Sudzha north toward Lgov and west toward Korenevo, the approximate Ukrainian-held area around Sudzha in mid-August, and the struck Seim bridges at Glushkovo, Zvannoye and Karyzh to the west — Figure 1. Schematic of the opening phase (6–21 Aug 2024). The held area reflects mid-August; positions, boundaries and scale are approximate. Does not show the current situation — Original graphic based on ISW assessment summaries (sources 3–5), Al Jazeera mapping (source 8) and Kyiv Independent (source 10)

Entry (6–7 August): After overnight drone and artillery fire, crossings were attempted at at least four points, two of which succeeded. Russia's Defence Ministry reported an attack by "up to 300" troops that had been repelled, then removed its claim of a Ukrainian retreat. ISW confirmed advances of up to 10 km by 7 August.
Expansion (8–12 August): Mobile groups drove deep along roads while follow-on forces consolidated. On 9 August Russia declared a counter-terrorism operation regime in Kursk, Belgorod and Bryansk oblasts under FSB leadership; ISW judged that this command arrangement could reduce the effectiveness of the response.
Sudzha and slowing (13–16 August): Pushes north toward Lgov and west toward Korenevo slowed as Russian reserves arrived. Ukraine announced control of Sudzha on 15 August. Some forward elements were reportedly ambushed after pressing too far ahead.
Flank isolation (16–21 August): According to Ukrainian statements, precision weapons put the Seim bridges at Glushkovo, Zvannoye and Karyzh out of action, and a Russian pontoon crossing had disappeared from satellite imagery by 19 August. Russian sustainment south of the Seim became much harder.

Timeline of the four phases from 6 to 21 August as date bars: entry 6–7, expansion 8–12, Sudzha and slowing 13–16, flank isolation 16–21. Below, markers for the 7 Aug advance of about 10 km, the 9 Aug Russian counter-terrorism regime, the 12 Aug claim of about 1,000 km², the 15 Aug Sudzha announcement, the pontoon gone by 19 Aug, and the 21 Aug claim of 1,263 km² — Figure 2. Timeline of the opening phase. Marker colours show the nature of the information (blue: Ukrainian statements and claims; red: Russian measures; amber: independent confirmation by ISW or imagery) — Original graphic based on sources 3, 5, 6, 9, 10 and 11

Decision Point Analysis

Matrix of the four decision points, setting the options considered beside the choices made: Decision 1 brigade-level entry into Kursk; Decision 2 drone and EW suppression plus electronic deception; Decision 3 a combination of local forces, units from other fronts and massed air power; Decision 4 isolation south of the Seim, in effect becoming a defence of the gains — Figure 3. Options and choices at each decision point. Amber outlines mark the options actually taken. Alternatives for Decision 2 are not confirmed in public sources; Decision 3 options follow ISW's 9 August assessment — Original graphic based on the analysis below and sources 4, 5 and 12

Decision 1: Axis and timing (Ukrainian high command) Options were (a) commit reserves to the Donbas defence, (b) limited cross-border raids, or (c) a brigade-level regular-force entry into Kursk. Option (c) was chosen, apparently to regain the initiative at a point where the defence was weak and the opponent's main forces were committed elsewhere. Surprise was achieved. The opportunity cost — reserves not available in the east — remains debated.

Decision 2: How to preserve surprise (Ukrainian operational echelon) Russia had already been warned. Ukrainian forces used drones and EW to suppress Russian reconnaissance UAVs just before entry, and a Western official has described electronic deception that drew Russian attention away from the main effort. Russia knew an incursion was possible but not its timing, scale or main direction. As ISW put it, surprise rested on ambiguity rather than on the opponent's ignorance.

Decision 3: The Russian response (Russian command) On 9 August ISW laid out four options: hold with local conscripts and border troops; commit the North grouping; redeploy reserves or better units from other fronts; or mass aviation and strike assets. Russia combined the counter-terrorism regime, local forces, units drawn from lower-priority sectors and air power, without significantly reducing the Pokrovsk effort. In the short term the lost area grew, but the momentum of the main eastern offensive was preserved.

Decision 4: Culmination and direction of exploitation (Ukraine) After Sudzha, the options were (a) a further deep thrust toward Kursk, (b) isolating the area south of the Seim to the west, or (c) transitioning to defence of the gains. In practice (b) was pursued through bridge strikes while the force effectively moved into (c). The salient was discussed as a bargaining asset, but once it became a fixed defence it was exposed for months to Russian counterattacks and pressure on its supply routes.

Lessons

Mission command: Rapid road-bound penetration with follow-on consolidation depends on initiative at low echelons; units that outran support risked isolation.
Combined arms and EW: A Western official assessed coordination between manoeuvre and EW units as tight, with good emissions control. EW proved more effective in fast manoeuvre than in attritional defence.
Surprise and intelligence: Warning is worthless unless it changes readiness. The Russian case shows the gap between intelligence judgment and unit preparation.
Sustainment: The deeper the salient, the longer and more drone-exposed the supply routes. Later Russian drone pressure on Ukrainian supply roads showed how costly it was to hold the initial gains.
Linking operations to strategy: Operational surprise does not automatically produce strategic effect; planners must account for the options the opponent is likely to choose.

Unresolved Questions

Area and settlement counts: Ukrainian claims (1,263 km², 93 settlements) differ markedly from ISW's estimate (about 800 km²) (Figure 4).
How many Russian troops were actually drawn from the Pokrovsk axis has not been independently verified; Ukrainian officials claimed a diversion effect.
The captured documents reported by The Guardian have not been independently authenticated.
Reports differ on which weapons were used against the Seim bridges.

Horizontal bar chart of area controlled: Ukrainian claim of about 1,000 km² on 12 August, Ukrainian claim of 1,263 km² and 93 settlements on 21 August, and ISW estimate of about 800 km² for the same period — Figure 4. Claimed area versus independent estimate. Methods differ, so the figures are not strictly comparable — Original graphic based on Ukrainian statements (source 6 and others) and ISW estimates (summaries in sources 3–5)

Sources

OSW, "Ukrainian military action in Kursk oblast" (2024-08-07). https://www.osw.waw.pl/en/publikacje/analyses/2024-08-07/ukrainian-military-action-kursk-oblast (accessed 2026-10-13)
Meduza, report on continued fighting in Kursk region (2024-08-07). https://meduza.io/en/feature/2024/08/07/fighting-continues-in-russia-s-kursk-region-as-ukrainian-troops-reportedly-advance-further-into-russian-territory (accessed 2026-10-13)
Kyiv Post, summary of ISW assessment of 7 August 2024. https://www.kyivpost.com/amp/post/37054 (accessed 2026-10-13)
Ukrainska Pravda, summary of ISW "operational surprise" assessment (2024-08-09). https://www.pravda.com.ua/eng/news/2024/08/09/7469611/ (accessed 2026-10-13)
Kyiv Post, summary of ISW assessment of 10 August 2024 (counter-terrorism regime, reinforcements). https://www.kyivpost.com/amp/post/37204 (accessed 2026-10-13)
Kyiv Independent, claim of control over 74 settlements (2024-08-13). https://kyivindependent.com/ukraine-controls-74-settlements-kursk/ (accessed 2026-10-13)
Meduza, "The Kursk gambit" (2024-08-14). https://meduza.io/en/feature/2024/08/14/the-kursk-gambit (accessed 2026-10-13)
Al Jazeera, mapping the Kursk incursion (2024-08-15). https://www.aljazeera.com/news/2024/8/15/mapping-ukraines-surprise-incursion-into-russias-kursk-region (accessed 2026-10-13)
AP (via Boston Globe), announcement of control of Sudzha (2024-08-15). https://www.bostonglobe.com/2024/08/15/world/ukraine-russia-sudzha-control/ (accessed 2026-10-13)
Kyiv Independent, strikes on Seim bridges and pontoon crossing (2024-08-21). https://kyivindependent.com/ukraines-special-forces-confirm-strike-on-kursk-oblast-pontoon-crossing/ (accessed 2026-10-13)
Kyiv Post, satellite imagery of the missing pontoon bridge. https://www.kyivpost.com/amp/post/37696 (accessed 2026-10-13)
Armada International, Ukrainian EW in the Kursk incursion (2024-10). https://www.armadainternational.com/2024/10/ukraine-electronic-warfare-kursk-incursion (accessed 2026-10-13)
RUSI, comment on Ukrainian drone tactics in the Kursk region. https://www.rusi.org/news-and-comment/in-the-news/ukrainian-drone-tactics-make-their-way-kursk-region-russian-military-bloggers-suggest (accessed 2026-10-13)
Novaya Gazeta Europe, summary of The Guardian's captured-documents report (2024-09-20). https://novayagazeta.eu/en/articles/2024/09/20/documents-reveal-russia-knew-of-ukraines-plans-for-kursk-incursion-months-in-advance-en-news (accessed 2026-10-13)
Euronews, analysis of Russian conscripts deployed to Kursk (2024-08-29). https://www.euronews.com/my-europe/2024/08/29/a-social-time-bomb-think-tank-believes-most-russians-fighting-in-kursk-are-conscripts (accessed 2026-10-13)
Meduza, Ukrainian withdrawal from Sudzha (2025-03-12). https://meduza.io/en/feature/2025/03/12/ukraine-withdraws-from-sudzha-amid-russian-advance-in-kursk-region (accessed 2026-10-13)
Wikimedia Commons, file page for the photo of central Sudzha (CC BY-SA 3.0). https://commons.wikimedia.org/wiki/File:%D0%A1%D1%83%D0%B4%D0%B6%D0%B0_%D1%81%D0%B2%D0%B5%D1%80%D1%85%D1%83.jpg (accessed 2026-10-13)
Wikimedia Commons, file page for the photo of the Seim River near Rylsk (CC BY-SA 4.0). https://commons.wikimedia.org/wiki/File:Rylsk._Seym_River_P5080397_2475.jpg (accessed 2026-10-13)