Revisiting Donald Rumsfeld's infamous 'known unknowns' quote

Donald Rumsfeld’s famous remark about ‘known unknowns’ was a response to questions about intelligence reports that failed to back his assertion that Iraq was supplying weapons of mass destruction.

Critics said the 12 February 2002 comment was an attempt to dismiss the lack of justification for military action.

Rumsfeld warned of “unknown unknowns” — things “we don’t know we don’t know.”“If one looks throughout the history of our country and other free countries, it is [these] ... that tend to be the difficult ones,” he said.