Ukraine Is Getting American M-1 Tanks. It Might Take A While.

When the Polish army went on one of history’s great tank-buying sprees starting a couple of years ago, it added to its multi-billion-dollar purchases of brand-new American M-1A2s and South Korean K-2s a side order of ex-U.S. Marine Corps M-1A1s.

Those M-1A1s are an important case-study. The work the U.S. government is doing to prepare those old tanks for transfer to Poland underscores the difficulty of sending similar M-1s to Ukraine.

The Poles are spending $16 billion to acquire 1,400 tanks—1,000 K-2s, 250 M-1A2s and 116 M-1A1s—to complement the roughly 240 German-made Leopard 2s Polish industry is upgrading, and replace the hundreds of locally-made PT-91s and ex-Soviet T-72s that Warsaw has pledged to Ukraine.

Local production of the K-2 gets underway in Poland in 2025. U.S. tank-maker General Dynamics should start delivering new M-1A2s around the same time. Polish officials assessed this two-year gap—between their tank donations to Ukraine and the arrival of new South Korean and American tanks—and ordered up 116 older M-1A1s as a stopgap.

But even these tanks won’t arrive quickly. The last of the M-1A1s Poland paid for back in December 2022 won’t reach Poland until December 2023. And there’s one main reason why. Their armor.

The M-1A1s Poland ordered are ex-U.S. Marine Corps models that became redundant when, in 2019, the Marines made the controversial decision to disband all their tank battalions. The move was part of the Corps’ comprehensive effort to make its forces lighter and thus easier to transport from island outpost to island outpost. The decision rendered redundant around 400 M-1A1s.

These ex-Marine M-1A1s aren’t quite as sophisticated as the U.S. Army’s newer M-1A2s are, but they do share guns, optics and armor with the Army models. That includes a super-hard, depleted-uranium mesh that General Dynamics inserts into steel “pouches” on the tanks’ turrets.

The mesh’s design remains a secret, two decades after its invention. And when America’s foreign allies buy M-1s, they get versions of the tank without the mesh.

Just one company is qualified to remove the mesh from existing M-1s—General Dynamics. So when Poland ordered those 116 ex-Marine M-1A1s, the U.S. Defense Department sole-sourced a contract with the firm to open up the tanks’ turret pouches and remove the uranium.

The deadline for the work is December 2023. It’s not clear General Dynamics can work any faster, considering its huge backlog of M-1 orders.

The U.S. Army is transforming some of the old Marine M-1A1s into Army M-1A2s, but that work apparently got underway just a few months ago. Subtracting the M-1A1s Poland is acquiring, there should be just shy of 300 ex-Marine tanks somewhere in General Dynamics’ modernization pipeline.

The United States so far has pledged to Ukraine 31 M-1s. The quickest delivery option might be for the Pentagon to divert some of the old Marine tanks. Not only would they share parts with the Polish M-1A1s, they also would need just a few modifications to make them exportable—foremost, the removal of any depleted uranium.

But even that could take a while, if the laborious process of prepping Poland’s tanks is any indication.