Once again, veteran White House correspondent Helen Thomas makes me proud to be a journalist.

Ms Thomas pushed a critical but still taboo question at a White House press conference the other day. 

She dared to ask top US administration officials why al-Qaeda and its affiliates continue to try and attack the American people.

The response by John O. Brennan was disappointing - but what many have come to expect from political appointees regardless of party affiliation.  Brennan, the advisor to President Obama on Homeland Security and Counterterrorism gave a response that evaded the truths he learned over 25 years in the intelligence field, with much of it spent in the Middle East.

I know this because I hosted Mr. Brennan on February 6, 2007 when I was director of programs at the Middle East Institute, America's oldest non-profit dedicated exclusively to educating the US public on the Arab and Muslim world.

Brennan had recently left the CIA as head of the National Counterterrorism Center and was working at a defence contracting firm in the Beltway.

When I asked Mr Brennan a similar question to Helen's, he gave our DC audience a different explanation.  Brennan used the analogy of "pollution" to describe al-Qaeda's phenomenon, likening al-Qaeda fighters to "pollution particles".

I'm paraphrasing now, but Brennan's memorable thesis was that "you don't declare war on 'particles', but  should instead look upstream to the sources of the pollution!"

Brennan then went on to discuss how US policy towards the Arab-Israeli conflict acts as a 'smokestack' for the pollution of terrorism.

It's disappointing that he has lost that candor. One could argue that the American public is better geared to have the painful "why they hate us" discussion now more than ever, as emotions were far too raw in the aftermath of the September 11th attacks.

There was a missed opportunity to open that discussion, but as veteran analyst Stephen Walt knows, dodging the al-Qaeda question has apparently become the norm.