We never agreed that when these talks , they would

This is an excerpt from the recent speech by NATO secretary-general Rutte. (link if needed)

In Washington, again NATO committed to future NATO membership for Ukraine, but it has never been agreed that whenever peace talks would start, that peace talks would end anywhere and always and definitely with NATO membership. That has never been agreed. It could be, but it never was that clearly stated. But I consistently have said is we have to make sure that whatever the outcome is we have to make sure that Vladimir Putin will never ever try again to attack Ukraine.

There may be some grammatical inconsistencies in this excerpt, but right now I want to focus specifically on "whenever peace talks would start that peace talks would end ...". Shouldn't that be "whenever peace talks started, they would end ..." instead? If not, could you please explain to me why that is correct. Thank you.

The phrase "whenever peace talks would start" is correct: the speaker is saying that NATO hasn't agreed upon when the peace talks would start. Further, he is saying that the peace talks have not yet (officially, technically) started.

Using "whenever peace talks started" indicates that the talks have, indeed, already begun, though the exact start date is either not known or is irrelevant to the point at hand. Consider Did Star Trek start airing in 1966 or 1967? No matter: whenever it started, I was living in Iowa and... where "I" acknowledge that I don't recall the exact year but move on to my larger point.

Here, I think the quote could be better-punctuated as: but it has never been agreed that - whenever peace talks would start - that peace talks would end anywhere and always and definitely with NATO membership. That is: "whenever peace talks would start" is a parenthetical notation; the speaker's larger point is "it has never been agreed that peace talks would end with NATO membership".