The announcement that the deal between Iran and the world's largest powers, led by the United States, to limit Tehran's nuclear ambitions went into effect early this week is indeed a historic development. The long history of animosity started shortly after the Iranian Revolution in 1979, with images of US diplomats in Tehran blindfolded and humiliated by young Iranians after the takeover of the American Embassy. A new chapter has been opened with this week's exchange of prisoners between the two countries, along with the nuclear deal. For the past 37 years, chants on Friday prayers in Iran started and ended with “Death to America,” “Death to Israel.” Tehran spared no effort to challenge US interests and allies, mainly oil-rich Arab Gulf countries, and slowly developed a viable nuclear programme that could be used to produce weapons. The US responded by freezing billions of dollars in Iranian assets and with a series of UN Security Council resolutions that imposed harsh sanctions against Iran, going as far as banning its oil exports and restricting its financial interactions with the rest of the world. Implementation of the nuclear agreement is likely to face many challenges, starting with the fact that the US president who worked hard to make it happen, Barack Obama, will leave the White House by early next year. The agreement faced strong opposition by Republican rivals, who went so far as inviting Israeli Prime Minister Binyamin Netanyahu to address the US Congress on the dangers of reaching a deal with Iran, and to bring more pressure on Obama. It certainly won't be easy to build trust between the two countries if one of the current Republican candidates for US president reaches the White House. Regional countries, namely Israel and most Arab Gulf countries, led by Saudi Arabia, do not welcome this agreement and continue to see Iran as a threat to their security. The deal signed between Iran, the five permanent members of the Security Council and Germany, includes no clauses that oblige Tehran to change its regional policies or interventions in the affairs of nearby countries. President Obama clearly attempted to calm their fears by announcing on Sunday that Washington will continue to support its allies in the Middle East region and imposed new sanctions on Tehran for violating a US ban on exporting ballistic missiles. Shortly after the Iranian Revolution, the new regime not only tried to destabilise regional security by “exporting” its revolutionary model, but also presented itself as the guardian of the Shia minority in the Middle East, inflaming a sectarian divide that dates back 14 centuries. The US invasion and occupation of Iraq in 2003 made things much worse, and revived Iranian ambitions to lead a Shia alliance that includes Iraq, Syria, Lebanon and Yemen. The strong support Tehran provided to Syrian President Bashar Al-Assad was clearly along sectarian lines, and orders were given to the Iranian-backed Hizbullah to send its fighters to Damascus instead of to Lebanon's borders with Israel. While preventing Iran from developing a military nuclear programme, averting a dangerous arms race, is indeed a positive development for regional security, Tehran must recognise that it needs to cooperate with its neighbours, and not just the United States and world powers, if it truly wants stability and a chance to rebuild its ruined economy, badly hit by years of tight sanctions. The recent flare up between Iran and Saudi Arabia following the attack on Riyadh's diplomatic missions in Tehran and Mashhad was only a taste of how events could dangerously escalate on the ground, despite the signing of the nuclear deal. The Saudi diplomatic missions in Iran were attacked after the execution of 47 Saudi nationals, including Shia religious leader Nimr Al-Nimr. Egypt's stand towards Iran has been balanced and based on a wait-and-see approach. Foreign Minister Sameh Shoukri was right to call on Iran to stop fuelling a sectarian war in the region if it wants to benefit from the nuclear deal, while recognising that the Shia minority in several Arab countries should enjoy equal rights and freedoms as citizens. Egypt, Shoukri asserted, will also always stand with its Arab Gulf neighbours against any Iranian attempts to dominate the region.