It looks to be a U.S. Army WWII Lensatic Compass. These would be used to take accurate bearings for land navigations, and were also used to direct artillery fire.
You should have a date on the botton of it.Yes it is US but WW2? they were made after ww2 also.
it's definately U.S., when I got out of the army in 96, we still had the same type, but the case was cheap plastic. I lost mine , wonder if it can find it's way home.
Thanks to all your comments guys... Yes, definitely a US compass. But I can't determined its era.. Try looking at the back closely, can't find any markings. It would have been easier..
looks like WW !! or Korea?
Thanks Franz! Could be Korean war era... There's a mile difference between our compasses.
Could be any era post WWII. I used these aluminum ones in the Army up to the mid 80's. Maybe the aluminum oxidation is hiding a mark somewhere.
Thanks to your comment George. I will check the compass again.