Ambassador Dennis Ross began his White House tenure with Jimmy Carter and ended it with Barack Obama, and has remained a consistent shaper of America's Middle East peace process under Democratic and Republican administrations.
Mr Ross's reputation as a skilled negotiator allowed him to transition from the administration of George HW Bush to that of Bill Clinton, where he was appointed special Middle East envoy reporting directly to the Oval Office.
The signing of the 1993 Israeli-Palestinian Declaration of Principles, known as the Oslo agreement, solidified his standing among world leaders.
As the Clinton years were winding down, Mr Ross says that no other president was more dedicated to Middle East peace, a bold statement given his past with the Carter administration.
After the election of George W Bush, Mr Ross returned to academia and the Washington Institute for Near East Policy, which he established with Martin Indyk, who was twice ambassador to Israel.
Mr Ross would later return to the White House as Barack Obama’s “Middle East quarterback”.
On September 11, 2001, he was giving a lecture at Johns Hopkins University's School of Advanced International Studies in Washington on the lessons of peacemaking in the Middle East, which was abruptly ended.
“There was almost a kind of cognitive dissonance," Mr Ross told The National. "It was hard to absorb how this was happening here.
In his career as a peacemaker and adviser, Mr Ross was no newcomer to extremist violence, but nothing compared to what was unfolding in real time on American soil.
He found himself in two minds: the one needing to know his family was OK and the one formulating a proper response for those relying on his judgment.
For the 20-year anniversary of those events, we asked Mr Ross for his reflections and predictions for US foreign policy.
THE NATIONAL: What was your first reaction that day? You’re a parent but also a negotiator.
MR ROSS: I was like everybody else, I was contending with a multitude of emotions, but then I had a career within the government dealing with different kinds of contingencies.
Part of my brain is saying, "I have to absorb this, but I also have to find out is everybody in my family OK, locate everyone." It's not the time to be moving around. We don't know if there are more attacks coming. Literally, two planes in New York, one here [in Washington]. Like you said, both sides of the brain.
TN: After locating your children, was your first impulse based on past experiences?
MR ROSS: First you’ve got to figure out who's behind this and create a reassurance. Then you start thinking about how you build coalitions.
I immediately began to think about, OK, how do we contend with this? And what do we know about it and how can we learn more about it and who else might help in this regard? How do you begin to build a response?
There were APCs (armoured personnel carriers) on the street in Washington and that made me think, ‘What's the reaction here at home going to be?’ What kind of law and order is there going to be?
That imagery of having armed personnel on our streets, this is not the America we've known.
TN: You once said that 9/11 was not about hitting the reset button on the Middle East peace process. Can you speak to that?
MR ROSS: This was a surprise of the order of Pearl Harbour. It was a shock. I think it created a profound sense of insecurity.
Any administration that was confronted with this would have reacted in a very strong fashion and would have had to reassure the American public.
No one knew what was coming next. Was this going to be the new norm? So the first thing was to establish the nature of the threat we're facing and how we contend with it.
And it wasn't related to peace-making in the Middle East because first of all, this was carried out by those who had no interest in peace.
TN: You objected to those who said it was about the Palestinian issue.
MR ROSS: Well, of course it wasn't about the Palestinian issue.
This was a reaction as much to the possibility that we were going to resolve it as it was the rejection of us and the perception of by Osama bin Laden and those who embody this ideology, that our mere existence represented a threat to Islam, at least the way they [Al Qaeda] interpreted Islam.
For me, this was on the one hand recognising those who carried out the attack and how would we have to deal with them in response.
What did this say about the region and what did it say about, in a sense, the struggle within Islam itself?
TN: What did you deduce?
MR ROSS: What bin Laden represented was a rejection of an interpretation of Islam that most Islamic scholars had embraced, which is that Islam was not about rejection. It was, in fact, a religion of peace, a religion of tolerance.
Those who embodied this extreme interpretation rejected the world of non-believers and felt that the world of non-believers, you couldn't deal with them passively. You had to attack them.
This was a war with the world of non-believers, but obviously we couldn't discredit them. That had to come from pious Muslims who would discredit these men and say that this isn't Islam, that this is a perversion of Islam and we have to do everything we can to discredit this because this is actually a threat to Islam.
The very perversion of it becomes a threat. And so the challenge is for us to work with Muslim-majority countries based on what was really a war of ideas.
TN: Since 9/11, how has your approach to foreign policy evolved or how did it change?
MR ROSS: While I had a lot of different roles in different administrations, in the Clinton administration, my role was defined because I was our envoy for Arab-Israeli peace. So my preoccupation was very heavily geared towards trying to promote that peace and how we promote those negotiations.
Terror was an issue because terror is what frequently derailed us. 9/11 obviously put a greater premium on focusing on the security side of this dimension, but as I said, it's still involved in a war of ideas. That meant identifying who our partners were and help making them more secure.
I will say one of the things that has influenced my view of Iran was that Iran was the driver of a lot of the terror bombings whose purpose was to disrupt and undermine the possibility of negotiating peace between Arabs and Israelis and Israelis and Palestinians.
Peace-making needs to take place in a context where those who pursue it can be secure from those who threaten them.
TN: What are your thoughts on Afghanistan, which was a response to 9/11, and moving forward?
MR ROSS: And Iraq was a response to this. There was an effort on the part of the [second] Bush administration to look at the war of ideas and feel that through the use of force we could create regime change.
And if there's one lesson we should have learnt by now, [it's that] we can't create from the outside a kind of political system that we would like to see in another country.
There is an interesting line we have to walk, not just in promoting our interests but also our values. We believe that certain values are universal and we can stand for those values. What we can't do is impose those values on others.
When you try to impose them, there's a contradiction. Our values are supposed to represent how we all define freedom; how we all define tolerance; how we define the approach to an election and then voluntary association.
That can't be imposed. It has to grow organically.
And if there's one thing we should have learnt if there are those within these other societies who want to promote these values, we have a responsibility, I think, to be helpful to them but we can't create it for them.