In June 2009, former US president Barack Obama delivered a speech from Cairo, addressing the entire Islamic world. For an hour, Muslims worldwide were promised a US administration that would be an unambiguous friend. A new, lofty American approach was promised, matched with quotations from the Quran and praise for the beauty of the Islamic tradition. Mr Obama became the man of the moment in the Middle East. And yet what followed in terms of policy implementation fell beyond most expectation. The early "Muslim ban" of President Donald Trump's administration, which now imposes stringent travel restrictions on citizens of 13 countries, could not have presented a greater contrast. It was seen by many as a blunt and unfair move – evidence of an American position of “guilty until proven innocent” towards people based on religion. Now, President-elect Joe Biden's incoming chief of staff has said the new administration will reverse the ban. Symbolically, this is a significant move. On a practical level, it could reunite families, allow talented Muslims to contribute to American society and reverse bizarre anomalies, such as complicated visa application procedures that apply to people with dual nationality from the banned countries. Despite the blunt tone of the ban, it is important to note that the precedent for making travel to the US harder for some Muslims was set in motion by Mr Obama. In 2015, his administration complicated visa applications for anyone from seven Muslim-majority countries, including Syria, Sudan, Iran and Iraq. The new measures also applied to people from any nation worldwide who had visited these countries labelled “countries of concern” after March 2011, or held dual citizenship. European citizens whose families hailed from those countries or held dual citizenship were also included in a measure the Obama administration said was addressing “the growing threat from foreign terrorist fighters”. Countries have the right to ensure their national security. Many tightened borders after a wave of uprisings in 2011 destabilised the Middle East and as the West experienced a wave of terror attacks – although some were committed by western citizens, not immigrants. This was partly motivated by domestic politics; fears over immigration throughout the West can now swing elections. All administrations, especially those who start from strongly idealistic positions, eventually have to confront the contradiction between lofty visions for a better future and the complex reality of realising one. For Mr Obama, the wet blankets were the financial crisis and a rapidly deteriorating situation in the Middle East. In Cairo, the region was promised prosperity. In reality, the Obama administration used 10 times as many drone strikes as those ordered during the entire Bush administration. Mr Biden's ideals will be dampened by an even tougher medley that includes the Covid-19 pandemic, climate change and more complicated geopolitics than four years ago. Many expect him to fill the vacuum created by Mr Trump's desire to withdraw the US from active global leadership. With America's departure, other nations have stepped into fill the void. It is harder to reclaim this space than it is to leave it. Managing a changed world requires new approaches. Mr Biden's proposed foreign policy team is experienced, but almost entirely drawn from the Obama era. They cannot afford to replicate the policies of old. The incoming administration is right to spot the important symbolism of revoking the "Muslim ban". But in order to confront the difficulties of today's unstable world, good oratory and ambitious promises will not be enough. Mr Biden will have to assess frankly how the world has changed and implement decisive measures in response.