anti-imperialist here refers to the American empire, which Israel is a tool of (and the U.S. serves Israel also, there is a symbiotic relationship).

> and then be trying to expand their empire into Palestine?

Not related to the above point, but this is happening in the West Bank anyway.

> There is another `anti-` that I would use here instead.

I doubt North Korea is doing this from a principled position of anti-Zionism