“The” Gedolim, Rabbi Shach especially, were against this so-called התגרות באומות, while most everyone else was strongly for it, and until today the debate rages on: Who was right?
In a footnote on p. 337 of “Rav Avigdor Miller – His Life And His Revolution”, by Rabbi Yaakov Y. Hamburger, the editor quotes Dr. Luchin’s “The Underground Press” (Judaica Press, 2014) who quotes Kissinger saying the protests only delayed the solution. Sounds to me like diplomatic grandstanding by an unreliable man.
On the other hand, Rabbi Meir Kahane’s columns in The Jewish Press reproduced letters received from Jews actually behind the Iron Curtain at the time claiming this strategy was best (they would know!).
Still, I think the jury is out.