Dina Esfandiary is an Iran specialist and a Research Associate in the Non-proliferation and Disarmament programme at the International Institute for Strategic Studies.

Iran's new president, Hassan Rouhani, was sworn in last Sunday. To slogans of 'Ahmadi Bye-Bye', President Ahmadinejad stepped down, leaving Rouhani with a country in turmoil.

The new president now faces a daunting task: to address the country's key political and economic problems, to deliver on his promise of change and to revaluate Iran's relations with its neighbours and the West, while having limited room for manoeuvre and facing staunch opposition from the Iran's conservatives. Can he deliver?

The Iranian political system is complicated. It is characterised by dynamism. It is not cohesive or uniform, and represents a multiplicity of views. It is not a one-man show – the Supreme Leader is the ultimate decision-maker but not the sole decision maker. Ruling by consensus is the name of the game. This explains the long-term stability of a system that has made many mistakes.

Constitutionally, the Iranian president has little power. Rouhani will be responsible for the Iranian economy (aka cleaning up Ahmadinejad's mess). But like past presidents, he may be able to influence the mood and direction the country is taking. More importantly, his position as a long-time insider will allow him to play the political game more effectively, while his good relationship with the Supreme Leader may mean that he will be able to sway Ayatollah Khamenei's views on certain issues.

There are two factors to consider: Rouhani's willingness and his ability to bring about change. Mohammad Khatami, Iran's former reformist president, was willing but unable to change anything — his hands were tied by Iran's hardliners. Under Rouhani it is likely that there will be change, but it will be moderate change without risk.

What will this mean for Iran's foreign policy?

Foreign policy is not the president's responsibility. It is controlled by Khamenei and the Revolutionary Guards. But Rouhani may be able to exert some influence. He has a good understanding of foreign policy, both because of his experience as Iran's nuclear negotiator and as the head of the Center for Strategic Research, a prolific Iranian think tank.

Rouhani's presidency could present an opportunity to re-examine the drivers of Iranian foreign policy. The traditional ideological driver of 'resistance' towards the West, represented by presidential candidate Saeed Jalili, was hugely unpopular in the elections. Rouhani has already spoken about 'reducing tensions', trying to mend relations with countries like Saudi Arabia and 'winning back trust'. His inauguration speech was delivered in a conciliatory tone, emphasising moderation, transparency and fairness in talks with the West. By choosing Mohammad Djavad Zarif as foreign minister, he made good on his promise to 'deliver a competent government'.

Yet it is unlikely that Iran's grand goals for the region will change. Its existing foreign policy principles are fairly entrenched. Rouhani also indicated that he will not deviate from current Iranian policy on certain regional issues, Syria in particular. Iran has invested too much in Syria and is using the crisis to demonstrate the power of its proxies. Rouhani will emphasise Iran's central role in finding a solution for Syria.

The real opportunity lies in the nuclear negotiations with the West. Rouhani's stance on the nuclear issue has led to optimism in the West, with the US stating that it would be a 'willing partner' if Iran 'engages seriously'. In a press conference in mid-June, Rouhani pledged greater transparency. He understands the give-and-take needed to hold purposeful talks, and is adept at the game of rhetoric: in October 2003, he agreed to a partial suspension of the enrichment programme, while bragging to domestic audiences that suspension was a tactical ploy to enable the nuclear program to advance in other ways. This allowed him to silence his hard-line critics, who were accusing him of selling Iran out.

For talks to succeed there will need to be decisive leadership on both sides. But Rouhani will need someone from the outside to confirm that Iran has an international partner and a reason to make concessions. If faced with inertia or a blind insistence on increasing sanctions, then hardliners will discredit him and Iran will revert back to a policy of resistance.

Rouhani's inauguration is cause for cautious optimism, but this will not lead to much if the international community is unable to respond to the opportunity his presidency represents.