The reactions across the Middle East to Joe Biden’s victory revealed the strategic calculations of leaders in the region heading into a post-Trump era.Driving the news: Some leaders quickly congratulated Biden while others hesitated. Some were restrained in their statements, while others couldn’t hide their joy at President Trump’s defeat.The first Arab leader to congratulate Biden, minutes after CNN called the race, was Egyptian President Abdel Fattah el-Sisi.Egypt is one of America's primary allies in the region and is perceived as the leader of the Arab world. Sisi, who also quickly congratulated Trump in 2016, was signaling that he wants to keep it that way.Trump's lauding of Sisi as "my favorite dictator” was a sharp break from Barack Obama, who responded coolly after Sisi seized power and never invited him to Washington.The friendly ties between Trump and Sisi date back to December 2016, when Sisi postponed a vote in the UN Security Council following a phone call with the president-elect.What to watch: Biden signaled during the campaign that, unlike Trump, he will push strongmen like Sisi on human rights.The second Arab leader to congratulate Biden was Lebanese President Michel Aoun, who is anxious to get off to a good start with Biden after a difficult stretch with Trump.The Trump administration has dialed up the pressure on the Lebanese government over the influence of Hezbollah, and it recently sanctioned Aoun’s son-in-law — former Lebanese Foreign Minister Gebran Bassil — for alleged corruption.King Abdullah of Jordan was also quick to congratulate Biden.Biden is expected to roll back some Trump policies that put Abdullah under massive pressure, including the severing of funding to the UN agency for Palestinian refugees (UNRWA), which affected millions of Palestinians in Jordan.Emirati Crown Prince Mohammed bin Zayed didn't hesitate in congratulating Biden either.The UAE has been preparing for a potential Biden victory for several months, and it made sure to get a blessing from Biden and other senior Democrats for its normalization deal with Israel.The Emiratis hope the goodwill they won with that deal will help them navigate Biden world, particularly given their concerns about a possible revival of the Iran nuclear deal.Palestinian President Mahmoud Abbas waited more than 12 hours to congratulate Biden.The main reason was that the Palestinian leadership wanted to see other reactions in the region and finesse the language it would use, Palestinian officials said.For the Palestinians, Biden’s victory ends four years of strong political and economic pressure from the Trump administration and three years with almost no contact with the White House.Palestinian leaders don’t expect Biden to revive the peace process, but they hope he will publicly reject Israeli annexation, roll back many of Trump’s decisions and return to a more traditional U.S. policy on the Israeli-Palestinian conflict.One outlier was the Saudi response. It took King Salman and Crown Prince Mohammed bin Salman 24 hours to issue a statement congratulating Biden.Between the lines: Saudi Arabia has faced sharp scrutiny in Washington during the Trump presidency, but not from Trump himself.He backed almost everything the Saudis did and took virtually no action over the killing of Washington Post columnist Jamal Khashoggi.Biden, by contrast, said during the campaign that Khashoggi was murdered on MBS' orders, stressed that he wouldn't sell weapons to the Saudis and promised to "make them the pariah that they are."The Saudis will likely try to avoid a clash with Biden however they can.Iran didn’t congratulate Biden, but many Iranian officials issued statements welcoming Trump’s defeat.Foreign Minister Mohammad Javad Zarif stressed that Iran would judge Biden on his deeds rather than his words.He also sent a message to Gulf states that aligned themselves with Trump, tweeting: “Trump's gone in 70 days. But we'll remain here forever. Betting on outsiders to provide security is never a good gamble."What’s next: The Biden administration will have many domestic challenges at the top of its priority list, and apart from Iran, the Middle East doesn't rank high on Biden's agenda.But as his predecessors have found, the Middle East will produce a lot of work for the new administration whether they like it or not.