Just going from memory here, but...

I recall that an arms reduction treaty was signed by, I think, Reagan that was very specific in what it covered. There was no lee-way given to either side on what had to be destroyed.

Destroyed is the word here. The 'weapon', and those trucks were considered weapons, had to be destroyed. Taken out of service was considered to be destroyed since neither side wanted to spend the money it would take to really 'destroy' what had to go.

At the time is was somewhat lamented, but the only solution was to go back and redo the treaty and neither side wanted to do this. So... Some machines were destroyed that could have been put to other uses.

I got involved in this when I was looking to buy some Russian rocket launch trucks to convert to oil-field equipment. Super cheap, crew cabs, eight wheel drive.... Real swamp buggies.

Sorry, they had to be 'destroyed'.