The Shape of Resistance: The Size and Structure of the Ukrainian Armed Forces

In the midst of total war, institutions are not merely tested—they are transformed. Nowhere is this more visible than in Ukraine’s Armed Forces, which since the full-scale invasion by the Russian Federation in February 2022 have grown from a peacetime military into a vast and complex war machine, improvised in real time and refined through fire. Yet numbers alone tell only part of the story. The structure, composition, and evolving doctrine of the Ukrainian Armed Forces (UAF) offer profound insights into the nation’s strategy, society, and statehood.

We consider here the size and structure of the UAF in 2025, analysing not only quantitative data but also organisational architecture, command philosophy, recruitment models and institutional tensions. We explore how Ukraine has balanced mass mobilisation with professionalisation, integrated irregular units into a national command, and evolved from a post-Soviet force into a NATO-adjacent hybrid of statecraft and survival.

From Skeleton Army to Total Defence

Before 2014, Ukraine’s Armed Forces numbered just under 130,000 active personnel, poorly equipped, underpaid, and trained primarily for ceremonial or internal tasks. The annexation of Crimea and the outbreak of the war in Donbas forced a hasty reconfiguration. By 2021, the UAF had grown to over 200,000.

The Russian full-scale invasion in 2022 catalysed the largest mobilisation in Europe since the Second World War. Within months, Ukraine declared martial law, suspended conscription age limits for men, and began absorbing hundreds of thousands of volunteers. By early 2024, estimates of the total Ukrainian military strength—active, reserve, and territorial—ranged between 800,000 and 1 million personnel according to the best data available.

These numbers are not merely the outcome of state planning; they are an expression of national mobilisation. Ukraine’s army is no longer a professional cadre force—it is a mass people’s army, integrated into society and reliant upon it.

The Core Forces: Ground, Air, and Sea

Ukraine’s regular armed forces are organised into five major service branches:

1. Ukrainian Ground Forces (Сухопутні війська)

The backbone of the UAF, the Ground Forces have expanded from 6 operational brigades in 2014 to over 60 manoeuvre brigades (multi-purpose modules capable of rapid deployment in a range of circumstances) by 2025, comprising mechanised infantry, armoured, artillery, airborne, and mountain units. They are supported by:

• Artillery brigades (both self-propelled and towed)

• Missile and rocket units, including HIMARS-equipped formations

• Engineering, logistics and medical support units

• Specialised drone and electronic warfare units

Brigades are increasingly modular, blending legacy Soviet systems (T-64 tanks, 2S1 Gvozdika artillery) with Western-supplied platforms (Leopard 2s, M109s, MRAPs).

2. Ukrainian Air Force (Повітряні сили)

Decimated in the early months of the war, the Air Force has shifted from traditional air superiority to air defence and strike integration. The force includes:

• Legacy MiG-29 and Su-27 fighter aircraft

• Limited Western systems (F-16s, as of mid-2025, remain in training phase)

• Robust ground-based air defence: NASAMS, IRIS-T, SAMP/T, and Patriot

• Strike drones and reconnaissance UAV squadrons

• Mobile radar and electronic countermeasure units

3. Ukrainian Navy (Військово-Морські Сили)

Though largely destroyed in the early stages of the war, the Navy has reconstituted itself along asymmetric lines:

• Small missile boats and drone boat squadrons

• Coastal defence units equipped with Neptune, Harpoon, and Storm Shadow missiles

• Naval infantry (marines), many of whom are redeployed as elite ground forces

• Danube-based river flotillas for logistics and patrol

4. Air Assault Forces (Десантно-штурмові війська)

These elite troops, Ukraine’s equivalent of paratroopers, have borne the brunt of many offensives. Numbering around 20,000, they operate with high autonomy, rapid mobility and strategic effect—though attrition rates have been severe.

5. Special Operations Forces (Сили спеціальних операцій)

Modelled on NATO doctrines, these highly-trained units conduct sabotage, reconnaissance, hostage rescue and psychological operations behind enemy lines. Despite their small size (around 2,000–4,000), their effect far exceeds their number.

The Territorial Defence Forces (TDF)

Perhaps the most distinctive feature of the UAF is its vast Territorial Defence Forces (Сили територіальної оборони). These are part-time and full-time regional units, formed largely from civilian volunteers, often aged 18–60. Their purposes include:

• Holding defensive lines in rear and urban areas

• Manning checkpoints and infrastructure security

• Reinforcing regular army brigades during surges

• Acting as a national reserve force

By mid-2024, the TDF included dozens of battalions, one in almost every region (oblast), with partial integration into central military command. Tensions persist over their autonomy, command coherence, and access to modern equipment—but their existence is a cornerstone of Ukraine’s “total defence” doctrine, in which every region defends itself.

Defence Intelligence and Cyber Forces

The UAF also includes sophisticated non-kinetic capabilities:

• GUR (Main Intelligence Directorate): conducts military intelligence, sabotage, and high-risk special missions.

  
  

• Cyber Command: engages in information warfare, electronic operations, and defence of critical infrastructure.

  
  

• Strategic Communications Units: play a key role in narrative warfare, countering Russian disinformation.

Civilian-Military Integration

Unlike many Western militaries, the UAF does not sit at arm’s length from society. Rather, it is embedded in the fabric of Ukrainian life:

• Volunteers and crowdfunding fill major supply gaps—from drones to boots.

• Veterans re-enlist in cycles, maintaining experienced cadre among fresh troops.

• Women now serve in greater numbers and in combat roles, particularly in drones, logistics and intelligence.

This integration brings moral strength but also strains—recruitment fatigue, PTSD, and growing tension between urban and rural mobilisation rates.

Command and Control: From Soviet Legacy to Mission Command

The Ukrainian command system has undergone a quiet revolution. While still partially based on hierarchical Soviet models, wartime necessity has forced the adoption of more flexible NATO-style “mission command”, particularly at brigade and battalion levels.

Key features include:

• Decentralised decision-making under broad strategic intent

• Rapid adaptation to battlefield dynamics

• Open-source intelligence integrated into operational planning

• Closer civilian-military cooperation in logistics and infrastructure repair

The General Staff retains overall command, but effective power is distributed—particularly amongst high-performing brigade commanders.

Strengths and Limitations

Strengths:

• High morale and ideological commitment

• Adaptability and battlefield innovation (especially with drones and digital systems)

• Interoperability with NATO standards in many areas

• A broad reserve of manpower, albeit variably trained

Limitations:

• Inconsistent training quality and rotation cycles

• Shortages of key personnel (NCOs, instructors, mechanics)

• Logistical and medical infrastructure under strain

• Fragmentation of command in certain TDF and volunteer units

• Increasing war weariness among the population

The Army That Ukraine Built

Ukraine’s Armed Forces in 2025 are not simply a military organisation—they are a mirror of the nation herself: resilient, improvised, decentralised, committed, and battle-hardened. They are at once a professional force and a national militia; a conventional army and a partisan network; a Soviet legacy and a European future.

This structure was not designed in peacetime but assembled in extremis. And yet it has proven effective against a numerically superior adversary, not by mimicking Russian mass, but by embodying Ukrainian will. The task now is to institutionalise this force: to build not just an army for survival, but an armed force for peace—integrated, professional, ethical and accountable.

In doing so, Ukraine may not only win the war, but also offer a new model for democratic defence in a dangerous world.