The Ukrainian military has recently unveiled several new army corps. The development is part of an ongoing reform in which Kyiv plans to replace problematic temporary command bodies with a host of permanent corps built around its best brigades and commanders.
The current system
Beginning in the 1990s, Ukraine gradually pared down the sizable military forces it inherited from the Soviet Union. Kyiv cut divisions down to brigades and eliminated army corps, with the last active-duty corps disbanded in 2015. The resulting force structure offered flexibility and reduced costs but was poorly suited to a major war during which the Ukrainian military has ballooned in size.
Kyiv currently uses a series of temporary bodies to exercise command and control over units in combat. Frontline brigades in eastern and southern Ukraine are subordinate to a tactical group (TGr), which is in turn subordinate to an operational-tactical group (OTU). Above the OTU is an operational or operational-strategic group of troops (OUV or OSUV). For example, OSUV “Khortytsia” is responsible for eastern Ukraine. It oversees several OTUs, such as OTU “Donetsk,” which is responsible for part of Donetsk Oblast. Under that OTU are multiple tactical groups, such as TGr “Pokrovsk,” responsible for the area around the city by that name.
On paper, Ukraine already has a handful of corps. In preparation for the 2023 counteroffensive, Ukraine established the 9th and 10th Army Corps under the Ground Forces. Kyiv later redesignated its Reserve Corps as the 11th Army Corps. In fall 2024, Ukraine formed the 12th Army Corps under the Ground Forces. Ukraine also created the 30th and 7th Corps, comprising its Marine and Air Assault units, respectively.
In practice, however, these are corps in name only. Their brigades are scattered between different groups of forces. Even where multiple units from the corps have operated alongside one another, such as during the 2023 counteroffensive, they’ve lacked corps-level support elements and the training necessary to function as cohesive formations.
Problems with the current system
The current system has contributed to various problems that the Ukrainian military hopes to address through the reintroduction of corps.
One issue is poor coordination between brigades. The TGr and OTU headquarters must often manage an unwieldy number of different brigades and other units. This sometimes leads to seams that the Russians have learned to exploit. At the same time, Ukrainian servicemen say these temporary commands often micromanage decision-making at the brigade level and below, even though many group commanders and staff officers have little to no combat experience and are removed from the situation on the ground.
Another complaint is that officers seconded to temporary commands rotate continually. Consequently, they lack the thorough familiarity with subordinate commanders, the strengths and limitations of their brigades, and the local terrain that a permanent corps commander would have. And because these officers know they will soon move on to other roles, they face insufficient accountability, Ukrainian servicemen argue.
Brigades themselves are often transferred between groups of forces. More problematic, battalions and companies frequently get split off from their parent formations and attached to other brigades to reinforce threatened areas, undermining cohesion (though Ukraine has recently sought to reduce this practice).
Ukrainian servicemen also say that because the temporary commands are responsible only for combat operations, not administrative control, they tend to prioritize short-term battlefield tasks (such as retaking a particular position) at the expense of preserving units’ combat effectiveness.
The transition to corps
Last November, the Ukrainian military revealed plans to transition to a “corps-brigade structure.” Brigades will be permanently subordinate to a particular corps, with each corps assigned its own stretch of frontage. The tactical and operational-tactical groups will be disbanded, while the operational/operational-strategic groups apparently will remain.
In total, Kyiv reportedly plans to have as many as 20 corps, including the existing ones, which will be turned into real corps. Compared to their US Army counterparts, the Ukrainian corps are closer to big divisions, with five or so maneuver brigades in each.
On April 25, Ukraine’s Air Assault Forces announced the formation of the new 8th Corps. This followed the unveiling of the 1st “Azov” Corps and the 2nd “Khartiia” Corps within the National Guard of Ukraine (NGU) in mid-April, as well as the 3rd Army Corps under the Ground Forces in March. A number of other corps are also known to be in the process of forming but have yet to be formally unveiled.
These four new corps are each based on some of Ukraine’s best brigades, whose commanders were tapped to lead the corps. Other personnel from those brigades will help staff the corps’ headquarters. When selecting corps commanders, Kyiv is generally prioritizing young, forward-thinking officers who have excelled as brigade commanders, as President Volodymyr Zelenskyy and his top general, Oleksandr Syrskyi, recently noted.
Kyiv hopes the transition to corps will allow its best brigades to rub off on other units, including by scaling quality training practices. (Ukrainian troops receive the bulk of their training in their units, often after lackluster basic training at training centers.)
Having decided on the commanders and composition of the corps, Ukraine is now working on forming these corps’ headquarters and units. According to Ukrainska Pravda, the corps commanders have received abbreviated training at the US Army’s School of Advanced Military Studies.
The corps structure
As recently noted by Brigadier General Oleksandr Pivnenko, the NGU commander, Kyiv intends to organize and equip the corps so they can conduct combat operations independently “without the need for constant involvement of the high command.” But exactly how the corps will be structured in terms of support elements—and when Ukraine will be able to fully man and equip all these units—remains unclear.
The 8th Corps has confirmed it will receive an artillery brigade (the 148th). Other corps likely will get artillery brigades as well, although Ukraine may have to form more if every corps is to get one, depending on how many corps end up being created. Additional support elements will likely include anti-aircraft, logistics, drone, electronic warfare, engineer-sapper, communications, and repair-restoration units, among others.
Many of these units are a work in progress. The 3rd Army Corps, for example, has begun forming a separate unmanned systems regiment led by a deputy commander from the 3rd Separate Assault Brigade, the main unit around which the corps is being formed. This regiment reportedly will be equipped with various types of unmanned aerial systems, including short- and long-range strike drones, as well as unmanned ground vehicles. The other corps may get similar regiments, a number of which Ukraine has recently established.
Ukraine is short on some corps-level capabilities. For example, unlike earlier Ukrainian corps, the current ones likely will not have army aviation units—at least not anytime soon—as Kyiv lacks enough helicopters. Likewise, although 3rd Corps commander Colonel Andriy Biletskyi has called for the corps to receive long-range precision-strike capabilities, it is unclear whether Kyiv will distribute its limited number of Western-supplied HIMARS and M270 multiple-launch rocket systems among the corps or keep them at the disposal of higher-echelon commanders.
Other challenges
One significant hurdle is that many of the brigades assigned to the new corps are currently fighting in completely different areas. Brigades will have to be redeployed so they can join their corps. This process will be difficult to execute, not least because Ukraine has few available reserves to replace withdrawn units. Russia has managed to exploit similar unit rotations in the past.
Another problem is a shortage of qualified officers. To function effectively, corps require both competent commanders and well-trained staff officers. A lack of qualified personnel is a key reason why Ukraine opted against adopting a corps-division-brigade structure, which it considered earlier in the war. As one officer explained to Ukrainska Pravda, the new corps have to take whomever they can get, and many of these people lack relevant experience.
A difficult reform with potential benefits
Even in peacetime, transitioning to corps would not be a quick or easy process. Doing so in the middle of a war is even harder. Time will tell whether Kyiv can pull it off before the war ends. However, if done right, this reform may better position Ukrainian forces to defend their country against current and future Russian offensives.
