Am I? I thought I'd seen it somewhere... though why Ukraine would have a trident is beyond me....
(and if it's the modern Ukraine flag you're talking about, that's actually NOT what I meant... I meant something that actually looks like a trident rather than abstract art, and on a darker blue like the French flag)
Come to think of it, I think where I might have seen the trident pattern was at a local university (whose team is called the Tritons); they have a bright gold (upright) trident on dark blue logo, if I recall. (For some reason about half the California public universities use blue and gold as their colors.)
Another possible idea you could use is the Barbados flag (see this link :
http://www.bgis.gov.bb/bgis/images/bigflag.jpg ) - I think someone was doing a set of modern countries so this may already be available.