Read this and answer the question. If the question is unanswerable, say "unanswerable".

On 16 September 2001, at Camp David, President George W. Bush used the phrase war on terrorism in an unscripted and controversial comment when he said, "This crusade – this war on terrorism – is going to take a while, ... " Bush later apologized for this remark due to the negative connotations the term crusade has to people, e.g. of Muslim faith. The word crusade was not used again. On 20 September 2001, during a televised address to a joint session of congress, Bush stated that, "(o)ur 'war on terror' begins with al-Qaeda, but it does not end there. It will not end until every terrorist group of global reach has been found, stopped, and defeated."

What day did George W. Bush apologize for the word crusade?
unanswerable