When I said off-road, I don't mean the capability to climb a very steep slope, or pass through deep water, I won't have that much expectation on a truck with simple chassis design.
What I mean is just the basic off-road performance, e.g. when only one wheel has traction and the remaining three all lost the traction (a very common situation when passing through bad roads that full of holes, or muds after a heavy rain), the vehicle should be able to pass by its own.
Check the following two videos, two Chinese SUVs, one pass the basic off-road test that I described, the other failed.
Success in the off road test:
http://v.youku.com/v_show/id_XMTI3MDQwNTkxMg==.html
Fail in the off road test:
http://www.autohome.com.cn/3788/0/27/Section.html?pvareaid=101505#maodian
The two vehicles shown are just for family purpose, therefore a success or failure on the off-road test doesn't matter that much. But for a military vehicle like the howitzer truck, the basic offroad performance is obviously a must-have.