Slovenia Is Giving Ukraine Some Very Old Tanks. But Age Can Be Deceiving.

Slovenia has announced it’s sending to Ukraine some very old tanks. As in, 70 years old, if you’re simply dating the original design.

But age might be deceiving in this case. The soon-to-be-ex-Slovenian tanks aren’t half-bad—especially compared to some of the museum pieces the Kremlin has sent to its own forces in Ukraine.

The tank is the M-55S. It’s a 1950s-vintage Soviet T-55 with upgrades. Lots of upgrades. Slovenian prime minister Robert Golob in a telephone conversation with German chancellor Olaf Scholz on Monday hammered out a deal whereby Germany would give Slovenia 40 military transport vehicles—and Slovenia in turn would supply 28 M-55Ss to Ukraine.

The M-55S is not the Slovenian army’s main tank. That would be the much newer M-84. The M-55Ss are in reserve.

On paper, a T-55—any T-55—is a hopelessly obsolete tank. While still popular in the developing world, the T-55 long ago disappeared from front-line units in reasonably modern armies.

But it’s a cheap and reliable platform. And a solid foundation for ambitious upgrades—few more ambitious than the M-55S. In the late 1990s, the Slovenian army paid Israeli firm Elbit and STO RAVNE in Slovenia to modify 30 T-55s. The companies delivered the last example in 1999.

The M-55S has a stabilized, British-made L7 105-millimeter main gun in place of the original Soviet 100-millimeter gun. The British gun is compatible with a wide range of modern ammunition, including armor-piercing sabot rounds that can penetrate the armor of a modern-ish T-72.

To point the gun, Elbit installed a new fire-control computer that allows the M-55S to shoot while moving. A T-55 normally stops before firing.

A T-55 has four crew—a commander, gunner, loader and driver. Only the gunner can aim the gun. The M-55S adds an independent sight for the commander so they can aim the gun, too.

For protection, the M-55S adds a laser-warning system that alerts the crew and deploys smoke grenades when an anti-tank missile is incoming. The Slovenian tank also has a new armor mix—explosive reactive blocks on top of passive armor.

Finally, a new engine with 600 horsepower, giving the 36-ton tank roughly the same mobility as a T-72. All that is to say, the M-55S isn’t really a T-55. It’s the bones of a T-55 with a new brain, new muscles and new skin.

And it should be a match for many of the Russian tanks in Ukraine—especially older T-72s as well as the T-62s the Kremlin pulled out of storage this summer to try to make good some of its losses.

Twenty-eight M-55Ss are enough for one battalion. It’s unclear when the ex-Slovenian tanks might arrive in Ukraine, and how quickly Ukrainian crews can train on their new-old tanks.