Western weapons are now being used in the fight for Ukraine. However, putting them into action on the front lines is causing serious problems for Ukraine’s military.

Ukrainian officials have portrayed Western arms as critical in their efforts to turn the tide of the war against Russia, which has been making grinding territorial gains in recent months—and they want more. Until recently, Ukraine relied on heavy weapons built or derived from Soviet-era systems, of which Russia has far superior equipment in far greater quantities.

Modern and effective Western weapons, particularly long-range artillery, are now on the battlefield. They are already making a difference, allowing Ukraine to launch precise strikes on vital ammunition dumps, air defense infrastructure, and command centers deep behind enemy lines, disrupting Russia’s offensive.

However, absorbing this new equipment, which is arriving in dribs and drabs from various Western countries, into the Ukrainian army is proving to be a significant challenge.

M777 towed howitzers from the United States, Australia, and Canada, as well as self-propelled howitzers such as the Caesar from France and the Panzerhaubitze 2000, or PzH 2000, from Germany—as well as the M109 from the United States and the AHS Krab from Poland—are being absorbed by the Ukrainian military.

Under standardization agreements known as Stanags, the North Atlantic Treaty Organization has attempted to standardize equipment such as ammunition so that it is interchangeable between nations and benefits from economies of scale. However, these standardization efforts have had little impact.

NATO has over 1,000 Stanags that establish common military standards for processes and materials, but each ally must decide which to implement. According to a NATO official, NATO leaders agreed last month in Madrid to assist Ukraine in transitioning from Soviet-era weapons to modern NATO weapons.

Ukraine has been given more than just different types of weapons. Its military must also learn to operate and maintain Western weapons, which are more difficult to operate and maintain than those it has previously used.

According to retired Lt. Gen. Ben Hodges, a former commander of the United States Army in Europe who is now with the Center for European Policy Analysis, the complexity is a trade-off for better performance. “There is a level of complexity that is required to achieve the higher level of capability that Western systems have, involving hydraulics, electronics, of the weapons systems, as well as the ammunition that is required to get to extra precision and range,” he said.

Some are 39-calibre systems, while others are 52-calibre systems, with corresponding ranges. They have different spare parts and maintenance requirements, as well as different loading mechanisms and charges. They may use proprietary computers, raising concerns about data transfer, and some may use proprietary shells. There are various training requirements for operating and maintaining the systems, as well as various parts supply chains.

Because some of these systems are provided in such small quantities, there aren’t enough pieces to rotate in and out of the front line for maintenance, so they must be withdrawn when they fail. Multiple artillery pieces with varying capabilities also pose difficulties for command-and-control systems and battlefield commanders.

Some of Ukraine’s artillery systems are particularly difficult to operate, particularly the powerful and capable German PzH 2000, which has very specific requirements for loading charges, among other things. To operate and maintain the system, Ukrainian troops required 40 days of training. It is also heavier than most Soviet-derived equipment, 57 metric tons, which means that some bridges aren’t strong enough to support its weight, potentially complicating its journey into the battlefield.

With only 12 such platforms sent by Germany and the Netherlands, the transportation problem is currently limited. However, weight would be an issue if Western nations began to send in battle tanks weighing up to 60 metric tons, which appears unlikely for the time being.

Nobody in the West believes that Ukraine would be better off without these new systems. Mr. Watling believes Ukraine’s Western supporters should learn a lesson and limit the number of different systems supplied in future supplies, such as armored personnel carriers and infantry fighting vehicles.