I have stumbled upon it in this article.
The nationalists are unconvinced by Mr Zelensky's promises to safeguard Ukraine's interests and not to cross his "red lines", set out in an urgent news briefing after the deal was signed:
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The expression "set out" has a number of definitions, but the relevant definition in this context is:
If you set out a number of facts, beliefs, or arguments, you explain them in writing or speech in a clear, organized way.
(Collins English dictionary)