RIYADH, Saudi Arabia—President Trump basked in this desert kingdom’s glitzy welcome as he announced an end to sanctions on Syria, signed investment deals with Saudi Arabia and issued a pointed warning to Iran.

On the first of a four-day Middle East visit, Trump sealed $300 billion in deals with the Saudis, with an eye toward doubling that total within four years. Heaping praise on the kingdom’s crown prince, Mohammed bin Salman , he encouraged Riyadh to move toward normalizing relations with Israel, despite the continuing war in Gaza that left Palestinians no closer to self-rule, a longstanding Saudi precondition.

Trump also issued an ultimatum to Iran as he aims to prevent the country from obtaining a nuclear weapon. “One way or another, make your move,” he said, adding the country would face “massive maximum pressure” if it doesn’t curb its nuclear work soon. “The offer will not last forever.”

Trump said he would lift U.S. sanctions against Syria , giving its new rulers a financial lifeline after a lightning campaign overthrew its decadeslong dictator late last year. The U.S. leader is expected to hold a brief meeting with new Syrian President Ahmed al-Sharaa Wednesday in the Saudi capital.

U.S. President Donald Trump and Saudi Crown Prince and Prime Minister Mohammed Bin Salman shake hands during a Memorandum of Understanding (MOU) signing ceremony at the Royal Court in Riyadh, Saudi Arabia, May 13, 2025. REUTERS/Brian Snyder TPX IMAGES OF THE DAY

“Now it’s their time to shine,” Trump said. “We’re taking them all off.”

His overarching message was that the U.S. will remain engaged and close to the region as long as its money pours into the American economy.

“You achieved a modern miracle, the Arabian way,” Trump said of the Gulf’s oil-rich monarchies. “The Gulf nations have shown this entire region a path towards safe and orderly societies with improving quality of life, flourishing economic growth, expanding personal freedoms and increasing responsibilities on the world stage.”

Trump’s visit to Riyadh kicked off with a Saudi F-15 escort as Air Force One touched down at King Khalid International Airport on Tuesday. Drums boomed and horns blared as Prince Mohammed, the country’s de facto ruler, greeted Trump on a lavender-colored carpet rolled out beneath the American plane. They then walked into the airport for a private ceremony, lined by waving U.S. and Saudi flags, to welcome the president and many of his senior officials, including Secretary of State Marco Rubio and Defense Secretary Pete Hegseth .

Trump and Mohammed also shook the hands of government and business dignitaries ahead of a lunch at the Royal Court, often stopping to speak at length with the most notable guests, who included billionaire Elon Musk and FIFA President Gianni Infantino .

But the region’s many challenges threatened to darken the cheery display.

Trump landed in a Middle East transformed by nearly two years of war after the Oct. 7, 2023, Hamas-led attacks on Israel, which responded with a military campaign in Gaza that killed tens of thousands of people. Another Israeli war last year against Hezbollah, the collapse of Syria’s longtime dictator and two direct exchanges of fire between Israel and Iran left Tehran greatly weakened.

U.S. President Donald Trump and Saudi Crown Prince Mohammed Bin Salman pose during a visit to At-Turaif World Heritage Site, in Diriyah, Saudi Arabia, May 13, 2025. REUTERS/Brian Snyder

Elon Musk stands during a visit to At-Turaif World Heritage Site, in Diriyah, Saudi Arabia, May 13, 2025. REUTERS/Brian Snyder

Syria’s new leader, Sharaa—an Islamist formerly aligned with Islamic State in Iraq and al Qaeda who is still designated by Washington as a terrorist—is trying to win U.S. support to rebuild Syria after more than a decade of civil war. He has sworn off his ties to radicalism and promised to run an inclusive government. He is reaching out through intermediaries to Israel and signaling willingness to let U.S. oil-and-gas companies work in the country.

Syrian government officials have said Sharaa wants to share with Trump his vision of a Marshall Plan-style reconstruction in which American and other Western companies would win out over China and other powers.

Trump said he announced the end of Syria sanctions after discussing it with Turkish President Recep Tayyip Erdogan and Prince Mohammed. “Oh, what I do for the crown prince,” Trump said.

Syrians celebrated the announcement, as did other countries in the region, including Jordan and Lebanon .

“We must give the new Syria a chance to rebuild and thrive. No guarantees, but if Syria is hampered economically, it almost assures chaos and openings for extremists,” said Dan Shapiro , a former Biden administration Pentagon official who oversaw the Middle East. “This is the right gamble.”

Others were less enthusiastic. Sen. Lindsey Graham (R., S.C.) noted that Syria is still designated by the U.S. as a state sponsor of terrorism and said a decision to lift that should be reviewed by Congress.

“Waiving congressionally-passed sanctions is a complicated process,” he said in a statement. “While I would like to empower the new players in Syria, it has to be done in a coordinated fashion with our allies—especially our friends in Israel—so that numerous security concerns can be addressed.”

Israeli Prime Minister Benjamin Netanyahu has demanded that southern Syria be “demilitarized” and said that the Syrian leadership’s forces won’t be allowed in the region.

Trump’s trip also brings the president to the shores across from Iran just as his administration is engaged in diplomatic efforts to curb Tehran’s nuclear program. A fourth round of talks between U.S. and Iranian officials on Sunday failed to make clear progress.

While Trump will be a quick plane ride from Israel, he isn’t scheduled to stop there, a glaring miss amid rising tensions with Netanyahu over Iran, persistent Houthi aggressions from Yemen and Gaza’s fate.

The U.S. president has struggled to broker a cease-fire and hostage-release deal in Gaza, which Riyadh wants before talking about normalizing relations with Israel. But Trump did succeed in getting Hamas on Monday to release the last living American hostage, Edan Alexander .

U.S. President Donald Trump and Saudi Crown Prince Mohammed Bin Salman pose during a visit to At-Turaif World Heritage Site, in Diriyah, Saudi Arabia, May 13, 2025. REUTERS/Brian Snyder

In his speech, Trump urged Saudi Arabia to join the Abraham Accords, the normalization pacts with Israel that allow for closer economic, political and cultural ties. Riyadh has resisted such a move after Israel’s attacks on Hamas in Gaza and rejection of a two-state solution. That didn’t stop Trump from pressing the issue.

“It will be a special day in the Middle East, with the whole world watching, when Saudi Arabia joins us, and you’ll be greatly honoring me, and you’ll be greatly honoring all of those people that have fought so hard for the Middle East,” Trump said, “but you’ll do it in your own time.”

And then there is a personal matter: how Trump and his family profit from foreign nations—including those on the itinerary—contributing to his cryptocurrency and branded projects. Trump is facing scrutiny over the administration’s talks with Doha about accepting a luxury Qatari plane as the new Air Force One.

The three Gulf nations will save sensitive foreign-policy issues for closed-door discussions. The public messaging will center on more closely aligning their economic interests with Washington’s.

Ahead of the trip, the State Department approved the possible sale of advanced air-to-air missiles and precision-guided weapons to Saudi Arabia. The Treasury Department announced plans to streamline how “ally and partner sources” can invest in the U.S. market that had long been pushed by the U.A.E. Qatar could get a deal for F-15 jet fighters and the U.A.E. might look to revive the purchase of F-35s that was promised at the end of Trump’s first term but blocked by former President Joe Biden , regional and U.S. officials said.

“Making deals isn’t just what Trump seeks to do, it’s his personal ideology. Every international interaction, whether with allies or adversaries, is in Trump’s mind supposed to lead to a deal,” said Stephen Wertheim , a senior fellow at the Carnegie Endowment for International Peace’s American Statecraft program.

Trump will end the Saudi leg of his trip with a Wednesday morning address at a summit of the Gulf Cooperation Council, a grouping of Arab countries established in the 1980s as a counterweight to Iran.

He will then fly to Doha for talks with Qatari Emir Sheikh Tamim bin Hamad al-Thani. The discussion is expected to include energy and investments but will likely focus more on foreign policy.

The trip concludes with a day in the U.A.E., which has pledged to invest $1.4 trillion in the U.S. over a decade.

Write to Stephen Kalin at stephen.kalin@wsj.com , Alexander Ward at alex.ward@wsj.com and Alex Leary at alex.leary@wsj.com