No single event has threatened the rule of Saudi Crown Prince Mohammed bin Salman more than the murder of dissident journalist Jamal Khashoggi in a Saudi consulate two years ago this week.

The grisly episode turned the leader, now 35, into a pariah as top political figures and business executives canceled and postponed meetings, the U.N. rights investigator declared the killing an “international crime,” and news media scrutinized the Saudi government’s shifting array of explanations and retractions related to the killing.

The decision by President Trump to back the young leader in the weeks and months after Khashoggi’s death proved critical to restoring the crown prince’s standing and propping up the Saudi kingdom’s tarnished image. “I saved his ass,” Trump said of Mohammed, according to a new book by veteran journalist Bob Woodward. “I was able to get Congress to leave him alone.”

The payoff for the crown prince is evident: The outrage has largely subsided, and he now regularly engages with the world’s political and financial elite. But the benefits for the Trump administration are far from clear, as the two governments remain at loggerheads over a range of economic, security and political issues on the second anniversary of Khashoggi’s death.

“The Saudis have mostly been a headache for this administration, despite its support for MBS,” said David Ottaway, a Saudi expert at the Wilson Center in Washington, using the initials of the crown prince. “Unless you’re an arms manufacturer, this relationship has offered minuses, not pluses.”

The president has long defended his decision to preserve the Saudi relationship as a means of protecting the billions of dollars of arms sales between the two countries every year. “They sent $400 billion over a fairly short period of time,” Trump told Woodward, referring to the deals struck in advance of his first trip to Saudi Arabia in 2017.

But the actual orders fell far short of $400 billion, and neither government has been able to substantiate where that figure came from.

Besides arms sales, however, the Trump administration has struggled to win Saudi cooperation on a number of pressing issues between the two countries.

The most glaring example is the U.S. demand to hold a credible investigation into the killing of Khashoggi, who on Oct. 2, 2018, was dismembered by a team of Saudi agents after he visited the Saudi Consulate in Istanbul to obtain documents that would allow him to marry his fiancee. Khashoggi, who wrote opinion columns for The Washington Post, had sharply criticized Mohammed’s consolidation of power and mishandling of the war in Yemen.

In the months following Khashoggi’s death, the CIA concluded with “medium to high confidence” that the crown prince had ordered the killing, which he has denied. U.S. officials said privately that some senior Saudi officials should face consequences, such as Saud al-Qahtani, a powerful royal media adviser, and Ahmed al-Assiri, a former deputy head of intelligence.

On Oct. 2, 2018, Saudi agents killed Washington Post columnist Jamal Khashoggi inside the Saudi Consulate in Istanbul. What has been done in the aftermath? (Joyce Lee, Thomas LeGro, Dalton Bennett, John Parks/The Washington Post)

Saudi prosecutors initially had said the two men played key roles in Khashoggi’s death, but both were exonerated by a Saudi court late last year.

In September, Saudi Arabia’s public prosecutor announced that eight people had been sentenced to prison terms of between seven and 20 years for the murder. The court sessions were closed to the public, and no senior officials were held to account in verdicts that the U.N. human rights expert tasked with investigating the killing said carried “no legal or moral legitimacy.”

“They came at the end of a process which was neither fair nor just, or transparent,” Agnès Callamard said in a statement at the time.

Secretary of State Mike Pompeo, who has long promised to get to the bottom of Khashoggi’s death, offered a terse remark to reporters on Friday acknowledging the anniversary of Khashoggi’s death.

“I don’t have much to update,” Pompeo said. “The Saudis have now prosecuted a handful of folks. We continue to press them to make sure we get as much as we can, that everyone who was responsible be held accountable. There’s not much of an update from where we were two months or four months ago.”

Besides falling short on the U.S. demand to hold a credible trial, the Saudi government has also defied the Trump administration in several other aspects of the bilateral relationship.

On the topic of nuclear nonproliferation, Riyadh has frustrated the Trump administration by resisting signing an agreement that includes strong international safeguards for its civilian nuclear program and prohibits the enrichment of uranium.

U.S. officials fear that the absence of such an agreement could trigger a nuclear arms race in the Middle East, one of the world’s most volatile regions. The State Department has said it opposes “the spread of enrichment and reprocessing” and urges the Saudi government to conclude an agreement.

The kingdom is also crosswise with the Trump administration on its blockade of Qatar, which hosts the largest U.S. military base in the region. Trump has personally appealed to the Saudi leadership to end the Persian Gulf feud, which is now in its fourth year, but the severing of land, air and sea routes into the small country remains in place, thwarting efforts at regional cooperation.

In a seemingly easier deliverable, Trump has asked the Saudis to provide airspace rights for Qatar Airways so the national carrier stops having to pay a reported $180 million in overflight fees every year to Iran, a country that the Trump administration is trying to squeeze economically and that is also an arch-nemesis of Saudi Arabia. Despite concerted efforts, no agreement has been concluded.

The U.S. energy relationship with Saudi Arabia, home to the world’s second-largest oil reserves, has long been cited as a rationale for close ties. But America’s recent energy boom has turned the two allies into competitors.

In the spring, the Saudis drew the ire of Republicans in Washington by sending throngs of tankers to the United States in what was widely seen as an attempt to flood U.S. oil markets with cheap crude. Local energy companies and U.S. lawmakers were so angry that they urged Trump to slap tariffs on the oil-rich ally.

“The Saudis tried to put the American fracking industry out of business,” Ottaway said. “A lot of companies had to shut down and it caused a huge headache.”

In Yemen, the Trump administration’s direct and indirect support for a Saudi-led coalition continues to associate the United States with the world’s worst humanitarian catastrophe. The Trump administration officially blames Iran for its support of Houthi rebels but has sought a diplomatic resolution to the conflict.

The Saudis also haven’t delivered for the president’s son-in-law, Jared Kushner, in the way many U.S. officials hoped they would. Since Trump came to power, Kushner has been the point man for dealing with the crown prince. A major premise behind the administration’s ambitious push to forge a “deal of the century” between Israelis and Palestinians was that Kushner’s close relationship with the Saudi leader could be leveraged to deliver the Palestinians to the negotiating table.

Despite the bond forged between Kushner and the crown prince, the initiative never got off the ground after the administration forced the Palestinians to swallow several concessions they viewed as red lines, including the United States recognizing Israel’s control of the Golan Heights, moving the U.S. Embassy from Tel Aviv to Jerusalem, and closing the Palestinian representative office in Washington.

Kushner also has sought to get Saudi Arabia to join Bahrain and the United Arab Emirates in normalizing relations with Israel. Such a commitment from Riyadh appears distant amid concerns about how the Saudi public and clerical establishment would view closer ties to Israel.

While the Trump administration has succeeded in keeping a steady flow of arms to Saudi Arabia, that component of the relationship has also caused headaches for officials who pursued the sales over the objections of Congress. Pompeo, who declared an emergency order last year to push $8.1 billion of arms sales to Saudi Arabia, became the target of an inspector general investigation over whether he acted improperly.

A report on the investigation, released in August, found that Pompeo followed appropriate procedures. But it also said his department failed to fully gauge the humanitarian consequences of arming the Gulf nations, which are responsible for the killing of numerous civilian casualties in bombing campaigns in Yemen.

Anger over what has widely been seen as a series of setbacks in the relationship have prompted calls for Democratic presidential nominee Joe Biden to reverse course with the Saudis should he prevail over Trump in the election.

A spokesman for the Biden campaign did not offer a response to questions about the matter. The White House and the Saudi Embassy in Washington also declined to comment.

“Biden has a unique opportunity to transform fundamentally a dysfunctional relationship with the Saudis,” said Bruce Riedel, a Saudi expert at the Brookings Institution. “We don’t need their oil. We don’t need their war in Yemen.”