From a recentN Korean parade. Its from the Arms Control Wonk blog and they also have no idea.
Why would you need MBRL towed by agricultural tractors? I know world food prices have gone up, but this seems a bit excessive.
Tractor is a sensible multi-use vehicle. Can be used for pulling those nameless farm implements or lethal military gear such as giant paper tubes that point at things.
One of the uses for such devices is to place them far from recognizable targets. If I had to tow something like that off-road, I’d want a tractor. Also, they go fairly slowly, which is desirable in a parade.
Plus, they’re red, and that seems to be the color of the day, judging by the background.
Or mules. But mules make for a messy parade.
And I think they may have eaten all the mules…
The only thing that makes a tractor into an artillery tractor is having artillery hooked up.
Tractors are quietly badass. When you get your fancy off-road vehicle stuck, you get a tractor to get it out. But if they are trying to make a military statement, it may be that “Every farmer in the countryside may be packing a tractor-deployable MLRS in their barn, so keep that in mind if you feel like invading.”
Of course, it’s hard to tell with the North Koreans. Maybe their economy is so bad that the only things they can keep running are essential vehicles. Maybe the next thing in the parade was ambulance-howitzers.
Or, they could be mock-up launchers.
Just cardboard, painted, & mounted on flatbeds.
That kind of thing, done to bulk-up a military on the tipping point, is a very real likelihood.
Same principle applies to volkswagens. 
Also, using tractors vs special vehicles shows thrift and responsibility.
Why not? They’ll probably get more use out of a farm tractor than a special vehicle just to pull some lightweight artillery launcher.
ISTR a story about a military parade in the USSR, where mobile ICBMs just kept circling the block to pass in front of the review stand again and again.
I don’t understand the confusion. Why wouldn’t you pull potato guns with tractors?
They may have done that too, but the case I’ve heard of was the 1955 Aviation Day military parade, where the Soviets flew the same 10 bombers over the reviewing stand a few times.
I like the theory in the comments at the blog story AK84’s talking about, that the tractors, (driven by women, according to the comment) are meant to show that all of NK society is committed to fighting the Yankee running dog oppressors. Not just the military. Incidentally, the MBRLs look flimsy as hell, but maybe that’s just a peculiarity of that model?
Loved the Charlie Stross reset in the comments too. I don’t think the Norks have shoggoth capability though.
Shouldn’t that be “Imperialist Yankee running dog oppressors”? And as for the flimsy appearance of the MBRLs, maybe that model is a one use only kind? There’s not much to the tube for a LAW, but after you shoot it, you don’t reload it, you just toss it away.
Are those white-wall tires on the missile lauchers?
Nobody said an army can’t have style. 
Might not need to be that sturdy- cardboard or thin fiberglass would work for a single shot.
Edit- a LAW rocket launcher case isn’t that tough. And professional fireworks use cardboard.