Not for me to say. I witnessed none of it. Though if you look at how leaders from the origins of Zionism openly claimed to have to "manufacture" threats to their own security, and match it up with the actions of the CIA and Mossad I'd say it's likely they/we at least knew about it prior. But again antisemitism is also a part of Zionist rhetoric. Saying Israel did anything is not inherently antisemitic.