The Ukrainian armed forces stood up around two dozen new brigades in the months leading up to its 2023 counteroffensive, which kicked off on June 4.

The Ukrainians equipped nine of these brigades mostly with Western-made tanks, fighting vehicles and artillery. The rest got maybe a battalion or two of European or American hardware and drew the rest of their heavy equipment from Ukraine’s deep stocks of ex-Soviet weaponry.

The army’s 22nd Mechanized Brigade is one of these hybrids. With its odd mix of PT-91, T-72AMT and T-72 Ural tanks, the 2,000-person 22nd Mechanized is representative of these hybrid brigades, which by now outnumber the nine largely NATO-style brigades.

They are, in a sense, the backbone of the Ukrainian ground forces as Russia’s wider war on Ukraine grinds toward its 17th month. What’s perhaps most notable is that many of these brigades have yet to appear along the front line in southern or eastern Ukraine.

They either are still training in the relative safety of northern or western Ukraine, or lingering in some staging area behind the main line of contact. Waiting, perhaps, for the Ukrainian general staff to decide when and where to deploy them.

The Ukrainian army had a 22nd Mechanized Brigade for around a decade after the collapse of the Soviet Union in 1991. But as the army withered for want of funding, many brigades folded—including the 22nd.

The Ukrainian defense ministry revived the 22nd Mech moniker late last year amid a huge expansion in the ground forces’ fighting strength. The army, marine corps, air-assault forces, territorials and national guard have stood up so many new brigades that planners in Kyiv are running out of numbers to assign to them.

At least, that is, as long as they continue to honor the armed forces’ naming conventions, whereby tank brigades generally have single-digit designations, mechanized brigades are in the mid-two-digits, light brigades choose from the 60s and 70s, air-assault units have 80s- and 90s-series designations and territorial brigades have numbers in the 100s.

The new 22nd Mechanized Brigade stood up apparently sometime late last year and began training around the western city of Lviv no later than February. While there were hints and rumors about the new brigade early this year, it wasn’t until last month that the brigade announced itself with a series of videos and photos its press department posted on social media.

The pics and videos depict a lot of the same old Soviet-made weaponry that equips most Ukrainian units. BMP-1 fighting vehicles. BM-21 rocket-launchers. 2S1 or 2S3 howitzers. ZU-23 anti-aircraft guns.

The unit’s tanks, however, are anything but typical. All three tanks types the brigade operates—in at least one battalion with around 30 tanks—are based on the classic Soviet T-72. But they include one of the newest and most sophisticated T-72 variants—and one of the oldest and least sophisticated.

The 22nd’s ex-Polish PT-91s are its best tanks. To produce a PT-91, Polish vehicle-maker Bumar-Labedy started with a 45-ton T-72M1—a downgraded export variant of the 1983-vintage, Soviet T-72A—and replaced the engine, transmission, fire-controls, optics and autoloader and added bricks of Polish-made Erawa reactive armor.

The result is a tank that still looks a lot like a T-72. Same silhouette. Same 125-millimeter 2A46 main gun. Same three-person crew. But it’s got an 850-horsepower diesel engine in place of the old, 780-horsepower model—making it several miles per hour faster. The neatly-fitted reactive armor offers better protection against high-explosive rounds.

The new fire-controls are the PT-91’s most important feature, however. The stabilizer on the T-72M1 is crude and requires frequent recalibration, limiting the tank’s accuracy while firing on the move. The PT-91 adds new, more robust, two-axis stabilization.

All that is to say, the PT-91 is a better tank than a 1980s-vintage T-72M1 is. With its modern optics, it stacks up reasonably well against the locally-made T-64BVs and donated Leopard 2s that equip other Ukrainian brigades.

Poland has donated to Ukraine at least 60 PT-91s along with hundreds of unimproved T-72M/M1s. The 117th Mechanized Brigade, part of the Western-equipped counteroffensive corps, reportedly got 31 of the PT-91s. It’s possible Kyiv doled out the rest of the Polish-made tanks piecemeal to other brigades.

The balance of the 22nd Brigade’s tanks are T-72AMTs and enhanced T-72 Urals. The uniquely-Ukrainian Т-72АМТ is a 50-year-old ex-Soviet T-72A with passive night-vision sights replacing the tank’s original night-fighting gear, which included active sights that worked in conjunction with an infrared spotlight.

It should go without saying that no sane tank crew would turn on a spotlight on a battlefield where enemy forces have their own infrared optics. The spotlight instantly would give away the crew’s position.

The active night sights also were one of the biggest problems with the T-72 Ural, which Soviet industry produced only briefly in the mid-1970s before switching to more sophisticated T-72 models with passive night-vision.

The Russian army recently has pulled some Urals out of long-term storage in order to make good its tank losses in Ukraine—2,070 destroyed, damaged and captured tanks and counting. The Ukrainian army, having lost more than 500 of its own tanks, has followed suit. The 22nd Brigade’s photos of restored Urals are some of the first evidence of the aged tanks in current Ukrainian service.

It’s apparent that Ukrainian industry—most likely the Malyshev Tank Plant in Kharkiv—has remedied the 50-year-old Ural’s biggest flaw. The infrared spotlight is gone, indicating the old tank now has passive night sights. Perhaps the same TPN-4 that Malyshev has installed in many other upgraded Ukrainian tanks.

On top of the new optics, the 22nd Mech’s old T-72s also have add-on reactive armor that can help to protect them from anti-tank missiles and high-explosive shells. Of course, none of this protects them from the biggest danger Ukrainian tanks have faced in the first three weeks of the southern counteroffensive: mines.

The 22nd Mechanized Brigade isn’t the best-equipped Ukrainian brigade. It isn’t the worst-equipped. What it is, is a reminder that the Ukrainian ground forces are mixing and matching new and old equipment in order to stand up as many brigades as they can.

As a result, Ukraine has ample reserve combat power. Uncommitted brigades it can deploy in order to exploit any gaps the committed brigades force open in Russian lines.