ΔE 14.2, fair: the same colour family, but not a straight swap. Olive Green (USAF) is noticeably darker, warmer than Dark Imperial Khaki.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Olive Green (USAF) is noticeably darker, warmer than Dark Imperial Khaki.
The same difference applies the other way round: Dark Imperial Khaki is noticeably lighter, cooler.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Dark Imperial Khaki on the colour wheel See Olive Green (USAF) on the colour wheel
All matches: Dark Imperial Khaki equivalents · Olive Green (USAF) equivalents