New U.N. plan on Iraq sought

Sought is the past tense of seek, seek means to look for or procure.

As an aside ICQ is derived from "I seek you".

Does the "New U.N. plan on Iraq sought" mean "New U.N. plan on Iraq that has been sought"?

It means "A New U.N. plan on Iraq is/was looked for"

It's in passive tense so it's a bit confusing but basically the headline is saying that someone (because it's passive tense it does not say who) is or was looking for a new U.N. plan for Iraq.

People like me don't really realise how confusing the English language can be, if it's not your first language. These questions are quite interesting.

Craven, I got it clearly. As to "is looked for" or "was looked for", depends on its context, right?
Wilso, you've hit it.