Western-made armor is failing in Ukraine because it wasn’t designed to sustain a conflict of this intensity, a military analyst told The Wall Street Journal.

Taras Chmut, a military analyst who’s the head of the Come Back Alive Foundation, which has raised money to purchase and provide arms and equipment to Ukraine, said that “a lot of Western armor doesn’t work here because it had been created not for an all-out war but for conflicts of low or medium intensity.”

“If you throw it into a mass offensive, it just doesn’t perform,” he said.

Chmut went on to say Ukraine’s Western allies should instead turn their attention to delivering simpler and cheaper systems, but in larger quantities, something Ukraine has repeatedly requested, the newspaper reported.