http://www.myanmar-information.net/infosheet/2003/030106.html
I found "inches" and "miles". However, travellers have told me that the distance markers on the road from Yangon to its airport are in kilometres, not miles. I also believe that old Burmese as well as inch-pound measures are used.
As for Liberia, I found from the official site:
http://www.allaboutliberia.com/
a distance measured in "kilometers", with no mention of miles.