The goal for these negotiations is to reach a mutually-agreed long-term comprehensive solution that would ensure Iranˈs nuclear program will be exclusively peaceful. (Source)
what does would imply here? If it implies future, why will has not been used?
A good link teaching would thoroughly would be really appreciated. Specially, distinguishing between the senses of would is not always easy.
I'm not sure you need a link explaining the full ins and outs of "would" in order to understand the answer to this question.
"Would" is (correctly) used in this sentence to express the fact that such a mutually-agreed long-term comprehensive solution does not currently exist, or at the very least, one has not been agreed upon. (This is a great example by the way, since various situations in Iran are/have been very difficult to resolve!)
We shouldn't use "will" (which would describe a concrete future), in cases such as these, where an outcome is very dependent on many factors (or conditions).
"Would" is the English language's conditional form. "Conditional" indicates that an outcome expressed with "would" is only possible if certain "conditions" are met. Think of "would" as "the furthest future possible".
I hope that at least answers your specific question.
To read more on "would", first check out its primary definitions (which give you some nice examples). This article also helps you on other aspects of this modal verb (past habits etc), and this article may also be of interest.
The difference in meaning is very slight, and I think "will" works okay in that sentence. Based on my American dialect, I would prefer to use "will" when I think the thing in question is very likely to actually take place, and "would" indicates that there is a strong doubt.
So in your example, I think the odds of negotiation perfectly satisfying everyone are low, so I prefer "would" in that sentence.
Contrary to the implications of the posted comment, I don't think there's any suggestion of "poor English" in using would rather than will in the first position within OP's cited context.
It's entirely a matter of stylistic choice whether they're seeking a solution that...
would ensure...
will ensure...
ensures...
It's also largely just a matter of style whether that the aim is that Iranˈs nuclear program...
would be exclusively peaceful.
will be exclusively peaceful.
...but it's probably fair to say is exclusively peaceful carries a stronger implication that Iran already has an ongoing nuclear program1 (the two "conditional/future" alternatives might be slightly more likely if no such program yet exists).
Having said that, an utterance which "stacks/cascades" two consecutive conditional or future tense verb forms might well be considered unnecessarily complex and therefore somewhat clumsy.
Most native speakers would probably prefer to use present tense for at least one of the two positions in OP's example. I've provided a link to the full context there, where I see no reason to take issue with any of the phrasing - it looks perfectly well written to me. The exact phrasing was probably hammered out over many hours of negotiation by many fluent speakers of English; repeated use of the conditional, which carries overtones of this is all somewhat provisional and speculative is quite natural in the context.
1 Or, as per StoneyB's comment, that the ongoing nuclear program is in fact "exclusively peaceful".
Contrary to the implications of the posted comment1, I don't think there's any suggestion of "poor English" in using would rather than will in the first position within OP's cited context.
It's entirely a matter of stylistic choice whether they're seeking a solution that...
would ensure...
will ensure...
ensures...
It's also largely just a matter of style whether that the aim is that Iranˈs nuclear program...
would be exclusively peaceful.
will be exclusively peaceful.
...but it's probably fair to say is exclusively peaceful carries a stronger implication that Iran already has an ongoing nuclear program2 (the two "conditional/future" alternatives might be slightly more likely if no such program yet exists).
Having said that, an utterance which "stacks/cascades" two consecutive conditional or future tense verb forms might well be considered unnecessarily complex and therefore somewhat clumsy.
Most native speakers would probably prefer to use present tense for at least one of the two positions in OP's example. I've provided a link to the full context there, where I see no reason to take issue with any of the phrasing - it looks perfectly well written to me. The exact phrasing was probably hammered out over many hours of negotiation by many fluent speakers of English; repeated use of the conditional, which carries overtones of this is all somewhat provisional and speculative is quite natural in the context.
1 Both footnotes refer to comments on the later duplicate question, where this answer was first posted.
2 Or, as per StoneyB's comment, that the ongoing nuclear program is in fact "exclusively peaceful".
"Will" has a more definite feeling of strength of one`s conviction about what they are saying.
"Would" leaves the door open for some doubt.
