following implementation of the nuclear accord.

Has the lifting of the sanctions brought the Islamic Republic in from the cold as a regional power in the middle east?

David Gardner, the FT's international affairs editor, joins me now.

David, what does implementation day really mean for Iran?

Is it completely different relationship that Iran can now have with the US?

It is a different relationship, it is, one shouldn't underestimate it, a golden moment for the Islamic Republic,

which has been regarded as a pariah state, a rogue state that was 37 years but over since 1979.

But above all, in the last as you know, dozen or so years, have these truly enveloping sanctions which have strangled its economy.

Um... I think definitely, it is being seen as an indispensable partner and player

in a region which is in meltdown and has so many problems.

I mean Iran is needed at the table on Syria, Iran cooperates with the US against ISIS and Iraq

and in so many other, conflictual situations from Lebanon to Yemen.

Well, it's very interesting that at a time when the Iranians and the Americans seem to be working much better together.

Iran's relations with its neighbors in the Arabia world have deteriorated significantly.

Do you think that Iran can be a stable force in the region?

It has a lot to do to become that.

To be regarded as a legitimate regional power,

it needs clearly to be seen by particularly the Sunni Arab power led by Saudi Arabia to pull in it's horns.

Um... to stop being seen as an aggressive actor taking advantage of the disintegration

because that is the worth of countries such as Iraq and Syria.

For whatever reasons that they started to disintegrate,

Iran has tended to work outside the state,

outside the institutions of these countries via agents such as militia to advance their interest.

But are you expecting the relationship between Iran and the Sunnie powers of the region

to deteriorate even further after implementation day?

There clearly is a feeling on the part of the Saudi is that all this comes at their expense.

Um... that has produced, in my judgement, a reactive policy.

Um... but at some point, this may settle if the principal actors in places such as Saudi Arabia and Iran

because clearly there needs to be some kind of dead-on between these two powers.

See it as in their interest to cooperate against common enemies such as ISIS.

We clearly haven't reached that point, far from it as you saw earlier this month

with the execution of Sheikh Nimr al-Nimr, Saudi Shia cleric.

Yet, at the same time in parallel you have processes,

the effort by the Saudis to put together some sort of viable Syrian opposition.

Let me ask you about oil.

Prices have gone down to 28 even below 28 today.

What do you think of the longer-term impact of Iran's return to the market as it's going to be?

I think there are two aspects to this.

Clearly, first of all, there is a huge unmet investment need in Iran

probably of the order of about a trillion dollars in the coming five years.

A great deal of that is in upgrading it's oil industry.

So the idea that they can suddenly turn on a tap is not the case.

So, I mean there is going to be an increase but I don't think it's going to be immediate.

But clearly overtime, it will have a softening effect on the oil price.

Iran is at the same time uh...

it is sitting on about 20% of the world's proven gas reserves,

a terribly important factor in a period when climate change is at the forefront of the international agenda.

Um... that is something I think which people would increasingly focus on and want to get into.

David, thanks very much. We've run out of time.