Would have

Here is a piece of the article from The Guardians.

His https://www.theguardian.com/media/ng-interactive/2021/may/07/we-were-there-the-guardians-most-memorable-journalism-over-200-years on a covert collaboration between the Reichswehr and the Soviet Red Army brought the German government to collapse. Other journalists would have known of the secret deal, which was common knowledge among European intelligence agencies, just as they would have known that making it public risked being sent to prison for treason in Germany. They decided not to publish. Voigt did.

Are these would haves non-conditional? Do they show presumption meaning? Please help.