when the Hamas attacks triggered the Israeli military offensive on Gaza.
They just triggered it! Wow, the guardian with rampant antisemitism there, denying that the Israeli government has any ability to make decisions for themselves.
Removing the passive voice would be something like "When Israel invaded Gaza in response to Hamas attacks" or "When the Israeli government launched a counterattack in response to Hamas led attacks" or so on.
It's the classic "Man shot when running from police" stuff, where one actor or actors are demphasised or erased in order to implicitly bias readership. It is especially notable when the most recent or destructive actions are passive voiced away.