AMMAN, Jordan — In a shabby state security court on the outskirts of the Jordanian capital, a highly unusual trial is unfolding that provides a rare glimpse into the kingdom’s fractured royal family, its tensions with more powerful neighbors in the region and its alliance with the United States.
It centers on a political intrigue, still somewhat shrouded in mystery, that came to light in April when Jordanian authorities made a sweep of arrests targeting powerful figures including a onetime heir to the throne and a confidant of the crown prince of Saudi Arabia, who is that country’s de facto ruler.
The confidant, Bassem Awadallah, is on trial along with a second defendant, Sharif Hassan bin Zaid, a businessman and distant cousin of Jordan’s King Abdullah II. Both have pleaded not guilty to charges of sedition and plotting to destabilize the monarchy and they face up to 20 years in prison if convicted. But the person at the center of the drama is missing from the courtroom: Prince Hamzah, the younger brother of the Jordanian king, has not been charged.
The trial has become a showcase of regional rivalries and is testing U.S. alliances with two important allies in the Middle East, Jordan and Saudi Arabia. Tensions between the neighboring Arab countries have arisen in part over the normalization deals between Israel and Gulf Arab countries reached last year.
The initial arrests in the sedition case shocked Jordanians and raised alarms among Western allies of Jordan, a small kingdom squeezed between Israel, the West Bank, Syria, Iraq and Saudi Arabia. The country has managed to maintain stability and take in waves of refugees from conflicts around the Middle East while remaining a loyal ally of the United States in intelligence, security and antiterrorism cooperation.
The trial has moved ahead despite intense pressure from Jordan’s more powerful neighbor, Saudi Arabia, to disrupt the proceedings.
The Saudis sent four jets with four different officials to ask for the return of Mr. Awadallah immediately after his arrest in April, according to a former senior Western intelligence official who asked to remain anonymous so he could discuss details on which he had been briefed.
He said those officials were headed by the Saudi foreign minister, Faisal bin Farhan, and included a senior official from the office of Crown Prince Mohammed bin Salman. They were joined by Saudi intelligence chief, who stayed in Jordan for five days to press the monarchy to allow Mr. Awadallah to return with him.
Saudi officials have confirmed that the delegation flew to Jordan, but said it was to express solidarity with King Abdullah, and denied that they were seeking Mr. Awadallah’s release.
“I think they pressed for the release of Awadallah because they knew he had incriminating information and they wanted him out,” said another former intelligence official, Bruce Riedel.
Mr. Riedel, a former C.I.A. officer, said Jordan was able to resist the Saudi pressure to return Mr. Awadallah after the C.I.A. director, William Burns, a former ambassador to Jordan, asked the White House to intervene. The C.I.A. declined to comment on the intervention.
But President Biden also called King Abdullah to convey his support while the Saudi intelligence chief was in Amman. And King Abdullah is scheduled to visit the White House next month.
The kind of support that the White House offered in April, at the height of the drama, would have been unlikely under the Trump administration, when relations between the two countries deteriorated to their worst point in decades.
Jordan initially blamed unnamed outside influences in announcing the alleged plot but has been careful since then not to antagonize Saudi Arabia, where hundreds of thousands of Jordanians are employed. If there were expelled, Jordan’s economy would face collapse.
Mr. Awadallah, now an economic adviser to the Saudi crown prince, was once one of the Jordanian king’s most trusted confidants, serving as the kingdom’s finance minister and then King Abdullah’s royal court chief. He holds Jordanian, American and Saudi citizenship.
The trial is closed to the public. But a video leaked from the courthouse on Monday showed a disheveled Mr. Awadallah dressed in a light blue prison uniform, his hands tied behind his back, led into the state security court through a door with pieces of the wooden frame missing.
Described as a driven and gifted economist, Mr. Awadallah possesses not just intimate knowledge of Saudi financial policy but of Jordanian economic deals, the former intelligence officials said.
“I would not be surprised if there is, in the end, a deal here or if Awadallah is found guilty but then sent into exile in the U.K. to keep his secrets to himself,” said Mr. Riedel, who has written a forthcoming book on Jordan and the United States.
Mr. Awadallah is accused of plotting with Prince Hamzah to destabilize the country. But one of the lingering mysteries in the murky case is what would have motivated him to do so.
Jordan, which has a majority Palestinian population, opposed key elements of former President Donald J. Trump’s normalization agreements between Gulf Arab states and Israel. One of the biggest prizes among those deals was an agreement with the United Arab Emirates — a close Saudi ally. Jordan fears the normalization pact will doom chances of an independent Palestinian state, as envisioned in its own 1994 peace treaty with Israel.
The aim of the plot, according to the charges, was to destabilize the country and “support the idea of Prince Hamzah becoming the ruler of Jordan.” Although Jordanian news media spoke at first of a coup attempt, intelligence officials say the accused plotters did not recruit military officials and stopped short of attempting to directly overthrow King Abdullah, who has reigned since 1999.
The former intelligence officials said Mr. Awadallah would have acted only with the approval of top Saudi leaders.
The former Western official said he thought the Saudis’ aim had been to undermine the king’s role as a pivotal player in the Middle East. A weaker King Abdullah would have less leeway to oppose policies regarding Israel and the Palestinians championed by the Saudi crown prince.
Prince Hamzah, 41, is an air force pilot who grew up as the designated heir to the Jordanian throne. He has had his movements and communications restricted since he was confined to his palace home in April and is not expected to be put on trial — probably to avoid the embarrassment of a senior royal facing prosecution.
Instead the palace announced a family reconciliation meeting headed by King Hussein’s brother, Prince Hassan. Shortly after, Prince Hamzah repledged his allegiance to King Abdullah.
According to the indictment revealed by state media, Prince Hamzah embarked on a campaign to undermine King Abdullah by meeting with disgruntled tribal figures to encourage protests against the king.
Hamzah, the son of King Hussein and his fourth and last wife, the American-born Queen Noor al-Hussein, had been groomed since he was a child to take over the throne. But in 1999, as the king was dying of cancer, he changed the succession to his eldest son, Prince Abdullah, who succeeded him later that year.
In 2004, King Abdullah stripped Prince Hamzah of the title of crown prince, transferring it to his own eldest son.
Jordanians say Prince Hamzah has deliberately cultivated speech patterns and mannerisms like his father’s and has never stopped aspiring to the role he and his mother insist he was born to inherit.
“The question is, is this basically it?” said Mr. Riedel. “He is certainly going to lie low for the foreseeable future but I don’t think his ambitions are going to go away.”