Challenges of mechanized and combined arms warfare: Lessons for Ukraine from Syria and Iraq

The flurry of announced plans to increase Western military aid to Ukraine continues. The United States and some North Atlantic Treaty Organization (NATO) allies have now pledged to deliver advanced infantry fighting vehicles and main battle tanks, and they are apparently considering advanced fighter jets, as well. If the West can deliver on its promises to equip and train Ukraine with these mechanized and armored ground combat vehicles in a timely manner, perhaps even before this spring, it could be a “game changer” — but not necessarily. Either outcome will likely depend on a range of factors, including details about what variants of what platforms the West provides; the level and quality of the training and logistics packages (hopefully) accompanying equipment delivery; the ability of Ukraine to actually generate combat power based on the provided equipment, training, and logistics; and the types of operations in which Ukraine employs said combat power.

Combined arms doctrine

Russia’s invasion of and ongoing war in Ukraine using mechanized and armored formations necessitated a range of Ukrainian responses, including resistance, defensive, and, increasingly, offensive operations. Ukrainian units have and continue to receive training in Europe on combined arms operations, as the combined effects of Ukrainian infantry, armor, artillery, engineers, and other combat arms will likely be necessary to dislodge Russian forces from the country, particularly given Russia’s long-term and ongoing improvements to its defensive positions. Combined arms combat operations are difficult, even for well-trained and well-equipped modern forces, and combined arms breaching of Russia’s defensive lines will likely prove similarly difficult, particularly at the battalion-, brigade-, or higher-level scale required. While Ukraine certainly has gained important combat experience over the last year, it has only slowly improved its ability to conduct combined arms operations. Even in the U.S. military and in NATO, few active service members have actual combat experience with the sort of large-scale mechanized and armor combined arms operations Ukraine is preparing to conduct, if only because such combat operations have been vanishingly rare over the last two decades.

The U.S. and NATO allies are training Ukrainian military units on combined arms operations, including on at least some of the platforms the U.S. has announced it plans to provide to Ukraine. The U.S. Army defines combined arms as:

“the synchronized and simultaneous application of arms to achieve an effect greater than if each element was used separately or sequentially. Leaders combine arms in complementary and reinforcing ways to protect capabilities and amplify their effects. Confronted with a constantly changing situation, leaders create new combinations of capabilities, methods, and effects to pose new dilemmas for adversaries. The combined arms approach to operations during competition, crisis, and armed conflict is foundational to exploiting capabilities from all domains and their dimensions.”

The idea of combined arms operations is, arguably, as old as organized violence itself, dating back to at least 3,000 BCE. Combined arms doctrine today finds its roots in ancient Greek and Persian warfare, and its more modern character can be traced to the deployment of armor, infantry, and artillery in 17th-century combat. In modern times, the invasions of Iraq in 1990/91 and 2003 perhaps best exemplify American large-scale, mechanized-armored combined arms operations. U.S. Army doctrine on these operations is broad and extensively elaborated. The war in Ukraine provides the most recent example.

Ukrainian combined arms operations

At the outset, there was “little evidence that the Ukrainians (were) executing joint and combined arms offensive operations.” But this has changed over time, as Ukraine shifted focus from resistance and defense to combined arms offensive operations and integrated additional combined arms training for its formations, much of which has been conducted by the U.S., in Germany. In this training, Ukrainian battalions “spend up to six weeks learning how to layer tanks, artillery and other weapons to maximize their effects ahead of an expected counteroffensive against Russian forces entrenched on Ukraine territory.” Now nearly a year into the war, Ukraine has clearly developed a combined arms doctrine and proven the ability to fight combined arms warfare effectively. As U.S. Army Lt. Col. (ret.) Amos C. Fox writes for the Association of the United States Army, “Ukraine’s tactical activity demonstrates a keen appreciation for, and ability to apply, combined arms. Ukraine has been able to compound the positive effect of micro-victories into tactical and operational success…[and] the Ukrainian military possesses a clear understanding of combined arms warfighting and a C2 [command and control] framework that facilitates combined arms operations.” However, combat losses — more than 400 tanks, more than 400 infantry fighting vehicles, and more than 700 wheeled vehicles — suggest a continued need for improving Ukrainian combined arms combat effectiveness. The Bradleys, Strykers, Abrams, Leopards, and Challengers the U.S. and NATO allies have pledged to Ukraine, as well as the accompanying training and logistics packages, respond to this need.

The difficulty of quickly providing mechanized and armored equipment to Ukraine, training Ukraine to employ this equipment in combined arms operations, and ensuring Ukraine can maintain and sustain combat power should not be underestimated. A large number of observers have already explained the challenge of converting equipment into combat power. These challenges include training on individual-, crew-, platoon-, company-, and higher-level tasks, which in mechanized and armored combined arms operations occur quickly, at least “10 times the speed of dismounted warfare.” Describing the immense challenge Ukraine faces in this process is almost beyond words: U.S. Army Lt. Col. (ret.) Daniel Davis wrote that he could not “stress enough how difficult it will be for Ukraine to produce mechanized forces of sufficient strength to expel Russian forces under current conditions.” Time constraints linked to expectations of spring offensives and training timelines for Ukraine appear to have been condensed from the year or so it normally takes a U.S. Army unit to complete a comprehensive training iteration. As fans of the Iron Triangle acknowledge, producing a thing quickly — in this case, combat power based on provided equipment — tends to have a negative tradeoff in terms of cost or quality. As cost seems not to be much of a factor, avoiding the good-fast-cheap dynamic may be possible. However, per the common law of business balance, exponentially accelerating Ukraine’s training timeline may very well produce a lower quality Ukrainian combined arms capability than desired.

Furthermore, a Ukrainian offensive to expel Russia from occupied Ukrainian territory appears likely to include one of the most difficult combined arms operations: large-scale breaching. U.S. Under Secretary of Defense for Policy Colin Kahl recently justified the provision of mechanized and armored platforms to Ukraine by explaining that Ukraine would need such equipment to breach Russian obstacles. As he explained, the “Russians are really digging in. They’re digging in. They’re digging trenches, they’re putting in these dragon’s teeth, laying mines.” U.S. Chairman of the Joint Chiefs of Staff General Mark Milley also recently assessed that it will “be very, very difficult to militarily eject the Russian forces from… every inch of Russian-occupied Ukraine. That doesn’t mean it can’t happen — doesn’t mean it won’t happen, but it’d be very, very difficult.” Notably, both of these U.S. senior leaders’ assessments acknowledge open source reporting that Russia has spent the last several months improving its defensive positions, including by expanding trenches, improving existing fortifications, and erecting new barriers, including miles and miles of new anti-tank ditches, barriers, and dragon’s teeth.

Vignettes: Operation Euphrates Shield and Operation Phantom Fury

But even less sophisticated mechanized and armored combined arms combat operations have recently proven difficult, with perhaps Turkey’s multiple incursions into northern Syria since 2016 providing informative examples. While the U.S. has also deployed mechanized forces to northern Syria, including Bradley Fighting Vehicles, these units have generally been employed in support of Syrian Democratic Forces or in security roles, such as guarding Syrian oil fields, not in the sort of combined arms maneuver for which Ukraine is training. Turkey, however, has conducted numerous combined arms operations in northern Syria and, as such, is one of only two NATO members (the other being France in Mali) to have actually deployed large-scale mechanized and/or armored forces in combined arms operations in combat in the last decade. In Operation Euphrates Shield (OES) in the fall of 2016, the first large-scale Turkish incursion into northern Syria, Turkey demonstrated “the continued relevance of land power for achieving strategic objectives.” And while Turkey successfully achieved its limited strategic objectives in each of its subsequent operations in northern Syria via the application of exemplary joint combined arms maneuver, the tactical and operational lessons learned from Turkey’s experience may be informative for understanding the sorts of challenges Ukraine will face against prepared Russian defensive positions — even though they are presumably far stronger than the militant groups Turkey contended with in northern Syria.

The major lesson learned from OES is that tanks are vulnerable on the modern battlefield, as both Ukraine and Russia have more recently learned. Notably, Turkey lost at least eight Leopard 2A4 tanks during its 2016 incursion into Syria, and perhaps as many as twelve. Of those, Turkey lost at least five tanks to anti-tank guided missiles (a deep analysis by Bellingcat walks through each Turkish battle casualty in detail). Based on this, one analyst has described the Leopard 2A4 as “not so good armor after all.”

Keen observers will note that Leopard 2A4s are, in some cases, the same variant of tanks NATO allies have announced they plan to provide Ukraine. In late January 2023, Ukraine announced that, in total, its partners had pledged to provide it 321 tanks, a number far higher than the 81 modern tanks pledged at the time by the U.S. (31 Abrams), Germany (14 Leopard 2A6s), the United Kingdom (14 Challenger 2s), Poland (14 Leopard 2s), Canada (4 Leopard 2s), Spain (Leopard 2Es and Leopard 2A4s, but of unstated quantity), Norway (8 Leopard 2A4s), the Netherlands (considering 18 Leopard 2A7s), Finland (Leopard 2A4s of unstated quantity), and Portugal (considering 4 Leopard 2A6NLs). Some of these tanks may fare better in Ukraine than Turkey’s Leopard 2A4s did in Syria, as many are more advanced variants than in the Turkish inventory, and since Turkey’s losses in Syria stemmed in part from instances of apparently inadequate tactical and operational employment of these assets. Germany, Denmark, and the Netherlands also plan to provide up to 178 older model Leopard 1 tanks to Ukraine, but many of these need to be refurbished, which entails a lengthy timeline. Whether or not Ukraine can successfully integrate these assets into combined arms operations remains to be seen, although Ukraine’s already-demonstrated combined arms capabilities suggest it may avoid the sorts of losses Turkey experienced in Syria.

Many readers — particularly those in the U.S., where anti-Turkey rhetoric in government and the media is prevalent, not least because Turkish incursions into northern Syria have targeted Syrian Kurdish forces with which the United States has chosen to partner in countering ISIS (despite the very real fact that these Syrian Kurdish forces profoundly overlap with the PKK, designated a foreign terrorist organization by the U.S.) — may find the Turkish example unconvincing or unappealing. As such, I offer a second, more relatable vignette: Operation Phantom Fury (OPF), in which U.S. forces cleared the Iraqi city of Fallujah in a large-scale combined arms combat operation in November 2004.

OPF may well be the last large-scale combined arms combat operation employing mechanized and armored forces along with motorized (wheeled) formations conducted by the U.S. military. In OPF, the 1st Marine Expeditionary Force’s Regimental Combat Team 1 (RCT-1) and Regimental Combat Team 7 (RCT-7) were reinforced by two U.S. Army mechanized battalion task forces (Task Force 2-7 Cavalry and Task Force 2-2 Infantry), an armor brigade (2nd Brigade, 1st Cavalry Division), and many other U.S. units and Iraqi Security Forces.

As Task Force 2-2 Infantry’s liaison officer to RCT-7 in the weeks leading up to OPF, and as a Task Force 2-2 Infantry battle captain assisting with command and control while forward on the battlefield with the command group during OPF, I have first-hand experience with the challenges of large-scale mechanized/armor combined arms operations in combat. Clearing and securing Fallujah required multiple synchronized combined arms breaches of major obstacles, including mines, improvised explosive devices, and defensive positions along the northern edge of the city that posed “a significant challenge getting into the city.” Breaching these obstacles was by no means a simple task. For example, 1st Battalion, 3rd Marines — tasked to open a breach in the center of RCT-7’s area of operation — failed to do so, despite several hours of attempts. In the end, 1st Battalion, 3rd Marines used Task Force 2-2 Infantry’s breach (itself secured with significant losses) to evacuate its casualties and move forces into the city. U.S. forces sustained significant casualties in OPF, with 82 killed in action and more than 600 wounded. OPF demonstrates that even for highly-trained and combat-hardened U.S. Marine Corps and Army units, combined arms combat operations — and, particularly, combined arms breaching — are extremely difficult.

As these two examples illustrate, and as the assessments by Kahl and Milley above suggest, dislodging Russia from its prepared defensive positions in Ukraine will be a daunting task for the Ukrainian military.

Jeff Jager, a retired U.S. Army Foreign Area Officer (FAO), served multiple FAO tours on the USEUCOM-USCENTCOM seam, including as an attaché in Cyprus, a U.S Army Training and Doctrine Command Liaison Officer Turkey, and a Foreign Military Sales Officer and ODC Chief in Lebanon. He also served as a military advisor at the Department of State. He is currently a Ph.D. student in Salve Regina University’s international relations program.

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