An American who goes by his call sign and holds, in his words, the illustrious rank of sergeant — the same one he had in the US Army, where he was a Bradley Master Gunner. He came to Ukraine in March 2022, was wounded almost immediately, and has been with the 3rd Assault Brigade since 2023. He is now the senior American military advisor to the Third Army Corps and its staff, and stood up its sergeant's course with his commander.

What is Operation Vivaldi?

Third Corps' offensive campaign in the Lyman direction, publicly acknowledged by the corps after months of total silence. Its stated objectives: defeat the northern pincer threatening the fortress belt around Sloviansk and Kramatorsk, and prove a multi-brigade corps can attack with minimal loss of life. The gains were still coming when this was recorded, which is why the operational details stay closed.

Why won't he give dates or details?

Because the weaknesses Third Corps exploited are still open, and they intend to keep them open. Concealment was vital — from the enemy and from friends: Russian commanders read OSINT to find out what is happening on their own front, so what gets geolocated on X reaches them too. He compares it to US practice, where the key exploits of a major operation surface ten years later.

What is the avalanche assault?

Jackie's name for the corps' method: build up effectors slowly, like snow accumulating on a mountain, without disturbing the visible pattern of life — then release everything at once. Ground drones appear behind the position, remote weapons open fire, infantry assault while the defenders are reacting to machines. The confusion is the breach.

What is the cappuccino line?

The most honest metric of the war, per Jackie: the last place behind the front where a barista will make you a cappuccino — the point where normal logistics, morale and civilian life still function. Ukraine's cappuccino line sits about 23 kilometres back. The mid-strike campaign has pushed Russia's to nearly 50.

What is Third Army Corps?

The corps built around the 3rd Assault Brigade, commanded by Andriy Biletsky, with roots in the volunteer units of 2014 and the defence of Mariupol. It grew from roughly 2,000 at the end of 2022 to 12,000 by the end of 2024, mostly volunteers, runs its own 51-day basic training and NCO academy, and has held Izium for two years. It now anchors Group of Forces Center, taking on the 11th and 19th Army Corps.

Who was Grady Kurpasi?

A retired US Marine with twenty years of service who came to Ukraine in 2022 and was killed that April. Jackie believes Kurpasi would have become the senior Western volunteer commander in Ukraine, and that he himself might have served as his sergeant major. The episode closes with his story — Sam calls it three minutes that are the best part of three hours.

When does the episode come out?

Soon — it is in final review. Join the waiting list on this page and you will get one email the moment it premieres on YouTube and Spotify; this page gets the player, the full transcript and the episode package at the same time. The runtime is 3 hours 5 minutes.

Operation Vivaldi From The Inside: Third Corps' American Advisor

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“Jackie” (call sign)

Rob Lee

Samuel P.N. Cook

Key takeaways

1For two years the verdict was that maneuver is dead: drones see everything, offense is suicide, the map cannot move. Third Corps ran a multi-brigade offensive in the Lyman direction anyway — Operation Vivaldi — and broke the northern jaw of Russia's pincer on Sloviansk and Kramatorsk, which was Russia's plan for the year. 250 prisoners, company commanders among them, 12,000 captured drones, hundreds of armoured vehicles.
2The exchange ratio was 20 Russians for one Ukrainian, on the offensive, with no extra mobilisation and no significant influx of casualties. The method: one squad of infantry is the only infantry effector whether the objective is squad, platoon or company sized, with over ten drone teams supporting it. The fewer men you offer up, the better the ratio.
3Jackie refuses to date the operation at all, even into the past, because the weaknesses Third Corps exploited are still open. Operational security had to be earned first: a corps with a record of clean, successful operations can ask for 11,000 artillery shells without explaining what they are for. A brigade with no reputation cannot.
4The avalanche assault: establish a pattern of life like snow falling on a mountain, load it slowly, then release everything at once — ground drones appearing behind Russian positions, remote-driven armoured vehicles packed with ammunition, every effector landing simultaneously on a defender who cannot respond. A remote-drive BTR-60 did route recon, mine clearing and fire drawing before it ever exploded.
5The mid-strike campaign pulls the Russian line back instead of pushing it: fight the supporting structure from one to 150 kilometres deep, force the cargo points and command posts back, and measure it by the cappuccino line — the last place you can get a barista-made cappuccino before the battle area. Ukraine's sits 23 kilometres back. Russia's is nearing 50.
6Technology is the least important layer. Third Corps cannot legally punish anyone — AWOL is not enforced — so discipline runs on trust, honesty and the after-action review, from Andriy Biletsky down. Its own 51-day basic training, a 24-day adaptation course for mobilised soldiers, an NCO academy built on the US Army's creed, and a brigade that grew from 2,000 to 12,000 almost entirely on volunteers.