Retired judge Eliahu Winograd presented the findings of the six-month investigation into the lead-up to war at a news conference.
He said the decision to launch the war without a well thought-out plan showed "a severe failure in judgment, responsibility and caution".
The aims of the war - to crush Hezbollah and force it to hand back two Israeli troops captured in a deadly cross-border raid - were "overly ambitious and impossible to achieve", Mr Winograd said.
He said the decision to launch the war without a well thought-out plan showed "a severe failure in judgment, responsibility and caution".
The aims of the war - to crush Hezbollah and force it to hand back two Israeli troops captured in a deadly cross-border raid - were "overly ambitious and impossible to achieve", Mr Winograd said.