(Bloomberg) -- Saudi Arabia reveled in Donald Trump’s decision to make the kingdom his first overseas destination as president. It will have to decide how welcoming to be for Joe Biden if he wins the White House in November.Trump’s May 2017 visit was marked by claims of $100 billion in arms sales, a traditional sword dance and a glowing orb meant to signal pan-Arab cooperation with the U.S. in the fight against terrorism. Since then ties have only become closer, with the U.S. pulling out of the 2015 nuclear deal with Iran, the president declining to implicate Saudi’s crown prince in the 2018 murder of columnist Jamal Khashoggi and the Pentagon sending forces to bolster Riyadh.Biden would be a change.The former vice president has described the kingdom as a “pariah” and threatened to stop the arms sales that make Saudi Arabia the U.S.’s top purchaser of weapons. He’s also signaled more willingness to engage with Iran, the kingdom’s archrival, and he’d probably work for a negotiated two-state solution to the Israeli-Palestinian conflict while essentially abandoning the Trump administration’s widely-panned efforts.All that means if Trump loses in November, Saudi Crown Prince Mohammed bin Salman “will need to decide if he is willing to roll out the red carpet for Biden and offer compromises on issues that the U.S. cares about either domestically or regionally,” said Ayham Kamel, the head of Middle East and North Africa at the Eurasia Group consultancy. “Saudi-U.S. cooperation will depend on efforts by both sides to define a new equilibrium in their relationship.”A Saudi official who asked not to be identified said that the kingdom has good relations with Trump, as was the case with his predecessors, and will continue to work closely with future presidents to strengthen relations between the two nations. Saudi Arabia’s relations have been a constant over the past 75 years under both Republican and Democratic administrations, the official said.Unlike some historic allies in Europe who have struggled with Trump’s more transactional “America First” approach to foreign policy, Saudi Arabia and many other Arab governments have viewed his administration as friendly to their interests and are concerned with how Biden may change that, according to three Arab diplomats in Washington.Taking on IranSaudi officials, who often had a contentious relationship with President Barack Obama and strongly opposed the Iran nuclear deal, were thrilled when Trump ended the U.S. commitment to the agreement with Iran and began ramping up sanctions on Tehran and countries doing business with it. The moves prompted Crown Prince Mohammed to say in 2018 that he loved working with the president. The prince has forged an especially close bond with Jared Kushner, Trump’s son-in-law and senior adviser.Yet not all of Trump’s Mideast initiatives were embraced in the region. His efforts to end the Israeli-Palestinian conflict alienated almost the entire Mideast, particularly after he moved the U.S. embassy to Jerusalem and recognized Israeli sovereignty over the long-disputed Golan Heights, seized from Syria in the 1967 Six-Day War. And he’s so far failed to end a Saudi-led blockage of Qatar, a key U.S. ally that hosts thousands of American troops.Democrat Biden has said he would “champion” the rights of Palestinians and Israelis to have a state of their own, contrasting it with Trump’s warm embrace of Prime Minister Benjamin Netanyahu. But Biden also downplayed suggestions that he would reverse Trump’s decision and move the U.S. embassy in Israel back to Tel Aviv.Unlike Trump, Biden has threatened to hold Crown Prince Mohammed accountable for the murder of Khashoggi, a U.S. resident and Washington Post columnist, at the Saudi consulate in Istanbul. He’s also criticized the kingdom for killing “innocent people” with American weapons, a reference to the Saudi-led conflict in Yemen that the UN calls the world’s worst humanitarian disaster.“Khashoggi was, in fact, murdered and dismembered, and I believe on the order of the crown prince,” Biden said in a Democratic debate late last year. “And I would make it very clear we were not going to, in fact, sell more weapons to them, we were going to, in fact, make them pay the price and make them, in fact, the pariah that they are. There’s very little social redeeming value of the -- in the present government in Saudi Arabia.”OPEC, WeaponsThe U.S. and the Al Saud monarchy have been strategic partners since King Abdulaziz Al Saud, Prince Mohammed’s grandfather and the founder of modern Saudi Arabia, met President Franklin D. Roosevelt aboard the USS Quincy in 1945. Oil for security has underpinned the relationship.The dynamics have shifted over time, from the OPEC oil embargo of 1973 to the 1991 Gulf War. The partnership survived criticism of Saudi Arabia as a breeding ground for extremism after 15 of the 19 hijackers on Sept. 11, 2001, were found to be Saudi citizens.Although the U.S. has reduced its longtime dependency on Saudi oil, the kingdom remains a formidable customer for American defense contractors and a regional bulwark against Iranian power.Under Obama and Biden, his vice president, differences emerged over the U.S. encouragement of the Arab Spring protests in 2011 and over Obama’s decision against engaging in a military confrontation with Syrian President Bashar al-Assad’s regime.Despite Biden’s denunciation of the humanitarian disaster in Yemen, the Obama administration aided Saudi Arabia’s air war with logistical support, intelligence sharing and munitions sales. During Obama’s two terms, the administration offered more than $115 billion in weapons to Saudi Arabia in 42 separate deals, more than any previous U.S. administration, according to data compiled in 2016 by William Hartung for the Security Assistance Monitor.The Biden campaign didn’t respond to requests for comment.The biggest concern for the Gulf states would be Biden’s approach to Iran. He’s already signaled he’d open talks with Tehran, although Iran’s leaders have said they’d never consider that unless U.S. sanctions are lifted.‘Strengthen’ AccordIf Iran were to recommit to its obligations under the nuclear accord, the U.S. would “strengthen and extend” the agreement, according to Biden’s campaign website.For the Saudis, the “Trump administration is their best bet,” Yasmine Farouk, a visiting scholar at the Carnegie Endowment for International Peace, said. “They no longer have illusions about the unpredictability of President Trump’s ‘America First’ foreign policy. However, they see in a Biden administration a return to Obama policies that are problematic to them and associate him with conciliatory policies toward Iran, political Islamists and a return of some support to democracy promotion.”Whether or not Biden’s approach would accomplish U.S. objectives, his Mideast strategy would probably win more backing in Europe, where the withdrawal from the nuclear deal and the Jerusalem embassy decision were widely criticized. European allies continue to argue that the nuclear agreement remains the best means for preventing, or at least delaying, Iran from obtaining nuclear weapons.“There is no other effective alternative around the corner,” European Union foreign-policy chief Josep Borrell told a July 14 online event organized by the Italian Institute for International Political Studies. “Without this deal, Iran could have gone nuclear right now. Right now, Iran would be a nuclear power, adding another factor of instability in a region which doesn’t need more instability.”There’s one area Biden and Trump appear to agree on: the need to shift more attention and resources to Asia, where the U.S. is increasingly in confrontation with China over everything from next-generation 5G telecommunications technology to freedom of navigation in the South China Sea and Beijing’s tightening grip over Hong Kong.“The Middle East is unlikely to be a Biden priority, and like Trump, Biden will likely want to reduce, not abandon the U.S. commitment to the region,” James Dorsey, a senior fellow at the S. Rajaratnam School of International Studies in Singapore. “China and Russia are bigger fish to fry.”For more articles like this, please visit us at bloomberg.comSubscribe now to stay ahead with the most trusted business news source.©2020 Bloomberg L.P.