Six months later, I found myself speaking with someone else about the UAE government and their use of mercenaries in conflicts around the Middle East and Africa when I asked, on a whim, whether they knew anything about Kushner and bank transfers from a UAE account. My acquaintance grew quiet. Then they replied, “Yes.”

When the Russian national arrived in England, the Dutch informed him that he had two options: he could work for them against the GRU, or the British would arrest him. Once in UK government custody, the operative would be charged with espionage. If convicted, he would spend years in a British prison. The Russian chose to change his employer.

Later that year, the Russian operative gave the Dutch spies access to one of the GRU’s most sensitive assets. Located in Rostov, Russia, the GRU’s hacking and cyber team operated a remote server on which they stored some of their bounty. During their search through these secret files, the Dutch found something astonishing: screenshots of Jared Kushner’s iPhone.

In The Hague, the MIVD hacking team tried to reverse engineer the Russian penetration of Kushner’s iPhone. Kushner owned what was then the latest model, the iPhone X. Released in November 2017, it featured Face ID, a state-of-the-art security feature that Apple had promoted at its launch. The Dutch team had been trying to pick the phone’s door lock, so to speak, when it occurred to them that the Russians may have found an unlocked window to gain entry instead. Their hypothesis was correct.

By early 2018, the MIVD had found a vulnerability in the iPhone that gave them access. The security exploit wasn’t perfect, however. Some malware allows a hacker to turn a victim’s phone into a microphone and video camera, turn the phone on or off, and pull and add files. The Dutch solution did not provide that level of access. Instead, when Kushner used the phone, they could see his screen. Almost as soon as they got inside, the intelligence service began capturing every image of Kushner’s screen as he used it, filing their own cache of surveillance on their internal computer servers.

As they monitored Kushner’s phone, they discovered he used it to to a UAE bank account. By the time the Dutch spies had visibility into the phone, the account had received hundreds of millions of dollars from a bank in Azerbaijan. Their initial assessment was that the bank account was affiliated with the government there.

For the MIVD hackers, the bank account became an intelligence mystery to unravel. Nearly everything they worked on had a tinge of Russian conspiracy. A little over a year into Trump’s first presidency, the MIVD, like FBI agents and federal prosecutors in Washington working on the Robert Mueller investigation, had only part of the story.

Kushner, UAE ruler Mohamed bin Zayed (MBZ) and Mohammed bin Salman (MBS) of Saudi Arabia, converged at an auspicious moment. MBS wanted to be crown prince. MBZ wanted to blow up Obama’s Iran nuclear deal, and Kushner wanted both to help him force the Palestinians into a deal that Israel would accept. Despite the perception of his wealth, Kushner was not entirely financially independent of his parents, and the family business, Kushner Companies, faced a billion-dollar loan coming due on their trophy property, the Manhattan office building at 666 Fifth Avenue.

Early in the first Trump administration, MBZ and MBS offered to pay for a slush fund dedicated to helping the new administration with foreign policy goals. The idea was to help pay for Trump’s promised wall between Mexico and the US, for example, in an effort to secure a second term in the White House. The two Arab royals initially discussed with Kushner putting more than $10 billion into the effort. Within months, though, as MBZ pushed the Trump administration to help back MBS’s effort to become his country’s crown prince—and future king—the broader foreign policy slush fund idea fizzled.

Instead, MBZ and MBS initially, and then MBZ alone, put at least $2 billion into at least two bank accounts for Kushner. It is unclear how the royals organized their $2 billion in combined payments, but they effectively split the cost. For the purposes of explanation, it is best to understand where and how each bank account was controlled.

Bank account Alpha was held at First Abu Dhabi Bank, the largest in the UAE, and was overseen by MBZ’s brother, Tahnoon bin Zayed, who served as the bank’s chairman. Beginning in 2017, the Saudis and Emiratis transferred roughly $750 million into the Alpha account. Alpha would be used as a foreign policy fund. This money would be overseen and partially managed by Kushner and MBZ, who, in their effort to strike a grand bargain to end the Israeli-Palestinian conflict, believed the region’s map needed to be redrawn.

“Jared was looking for shortcuts in his diplomacy,” a source who knew of the UAE’s deal with Kushner said. This person held discussions with both senior UAE and Israeli officials about the secret financial arrangement between Kushner, the UAE, and, at least initially, Saudi Arabia. “Jared promised MBZ that he’d push their agenda with Trump if they participated in a fund. He wanted normalization with Israel so that business could take off.”

A slush fund—a shared pool of money for off-the-books diplomatic objectives—was a common form of Gulf Arab government corruption, this person explained. “The Emiratis and the Saudis do this once a year. A billion or two is nothing for them, and if it gets them what they want, it’s money well spent.”The Alpha account looked like the funding source of a UAE government program, by which MBZ paid his bureaucrats their salaries or funded government-run schools.

But how and through whom the money flowed into the Alpha account revealed that it was intended to remain secret, more akin to a covert and illicit scheme, given that it was managed in part by a senior advisor to the president of the United States.

The Dutch spies who monitored the Alpha account noted that all of it was sent by a bank in Azerbaijan in American dollars. Azerbaijan plays a unique role in money laundering. Its central bank maintains high levels of US dollars in its reserves but does not adhere to the highest standards of bank transparency. As a result, Azerbaijani banks have well-established but unadvertised practices of serving as way stations for large transfers, in which a foreign currency is exchanged for an equal amount in dollars. For a roughly 6 to 7 percent fee on the transaction, some Azerbaijani banks will accept a transfer from a client who wishes to move Saudi riyals or Emirati dirhams totaling hundreds of millions of dollars.

The Saudi or Emirati client sends the money to the Azerbaijani bank, which then uses a different internal bank account to transfer the equivalent US dollars to the client’s requested destination. For auditors, this shadow trade can’t be discerned.

A shallow audit, as the Dutch tried while monitoring Kushner’s iPhone, revealed nothing more than what appeared to be an Azerbaijani government–linked bank account that sent hundreds of millions of dollars to an account in Dubai. But there was another aspect of the Alpha account that the Dutch couldn’t see or understand, one that helped reveal the secret purpose of the money. Kushner did not own the bank account at First Abu Dhabi Bank. He was a signatory for an account managed and owned by an Emirati charity.

When MBZ and MBS first began contributing to the Alpha account in 2017, the Watani Al Emarat Foundation, a UAE government-funded charity, was run by Dherar Belhoul Al Falasi. Al Falasi was a technocrat and a member of the Federal National Council, and friends with one of MBZ’s closest friends and advisors.

As a result, Al Falasi and the Watani Foundation had a second mission. The charity was used as a cover to move money in support of the country’s secret military and intelligence operations overseas. Under the Watani cover, Al Falasi helped facilitate the UAE’s secret weapons-purchasing programs, one confidential source who had direct knowledge of the charity’s proliferation program revealed. This source said that the Emiratis believed that the program’s status as a charity made its international transactions less likely to be scrutinized and therefore served as a useful cover for funding MBZ and his brother’s secret wars.

MBZ and Tahnoon made Kushner a signatory on the Alpha account with Watani. As a signatory, Jared had access to it and could, in theory, make transactions, but it technically wasn’t his account. One way to view what Kushner did with the Alpha account is to imagine him as the director of the CIA. Had he been running the government entity that managed and ran secret foreign programs, maintaining the account, again, with presidential approval and congressional disclosure, Kushner’s conduct would have been within his job’s responsibilities.

But he was not the director of the CIA, whose position is approved by the Senate and whose operations are overseen and accountable to Congress. Instead, Kushner was overseen only by his father-in-law, who, according to four senior Trump administration officials—two national security advisors, a White House chief of staff, and a former CIA director—were unaware of any presidential authorization for Kushner to access a foreign government bank account. (Kushner’s counsel, however, said Kushner did not make any agreements or arrangements with leaders or officials in foreign countries that were not agreed to by the President of the United States and in the best interests of the United States.)

Regardless of whether he was a signatory or the owner, Jared was required by federal government regulations and the Internal Revenue Service to disclose his access to the account. Unless disclosed to and approved by the US government and reported on his tax returns, Kushner’s access to the Alpha account may have violated US law. (A lawyer for Mr. Kushner denied that his client had any knowledge of or connection to Al Falasi, the Watani charity, or a UAE bank account and stated that he had complied with all legal requirements when dealing with foreign governments.) In addition to the Alpha bank account, MBZ put money into at least one other account intended for Kushner.

By the spring of 2018, the crown prince had moved roughly $1 billion to Israel via Azerbaijan for Kushner. We will refer to this account as the Beta bank account. It is unclear how Israeli Prime Minister Benjamin Netanyahu first learned of MBZ’s money for Kushner, but a person briefed on the Beta account told me that the prime minister encouraged Kushner to have the money deposited in the Israeli Central Bank, in what would appear to be a government account.

It is also unclear how Kushner used the money the UAE deposited into the Beta account for him, but according to the person with knowledge of the money, its allocation was for Kushner’s personal benefit. But as with the Alpha account, there were clues in the way the Beta account was managed.

Israel’s Central Bank does not operate personal accounts. The bank holds and transfers only government funds. The government accounts use a dual-key system, which requires two authorized individuals to make any transfers from the account as an oversight mechanism. Netanyahu required Kushner to inform him before making any transactions from the Beta account.

To do so, Kushner passed his messages through Ambassador David M. Friedman, who frequently met with Netanyahu. With the money in the Central Bank, it would be difficult, if not impossible, to connect MBZ’s payment to Jared. It is unclear if spies in the Netherlands had any indication of the Beta account. (Ambassador Friedman denied that he had any knowledge of, or involvement with, any UAE money made available to Kushner, or that he passed messages on Kushner’s behalf. “I know absolutely nothing about any of these allegations,” Friedman said, “and the specific allegations about me or my alleged involvement in this alleged scheme are 100% false.” Kushner’s counsel also said Kushner “has no idea” about any such account, and insisted that “there are no accounts and never were.”)

Apparently, Kushner faced the challenge of moving money from the Beta account in Israel to other accounts where he could have untraceable access to the funds. One person who worked with Kushner to move the money out of Israel said that much of it went to bank accounts in Cyprus before being moved elsewhere.

During Kushner’s secret financial arrangement with MBZ, he helped negotiate a third, altogether distinct account. As part of what was, at the time, a secret warming of diplomatic relations between Israel and the UAE, Kushner helped negotiate an agreement by Israel to help defend the UAE from a major Iranian military attack. The UAE needed to cover the cost of the emergency defense, however, and the government secretly made another transfer to Israel’s Central Bank. This was something like a rainy-day defense fund. Combined, the three accounts represented a secret foreign policy negotiated by Kushner with the leaders of Israel, the UAE and Saudi Arabia.

Although Kushner’s position as senior advisor to the president was unpaid, he was an official government employee. Not only did his position require financial disclosures for ethics regulations, but each year he worked in the White House, he had to file both a public and confidential financial form, known as the Executive Branch Personnel Public Financial Disclosure Report, also known as a 278e disclosure. Because he had access to classified government secrets, Kushner was required to disclose any bank account to which he had signatory—or beneficiary—access.

Kushner’s apparent betrayal of the public trust, however, went further than his failure to disclose the secret Alpha account in the UAE or the Beta account in Israel. By giving him access to roughly $2 billion, regardless of how the money was used, MBZ and MBS were paying for his influence within the US government. Any efforts he made to shape US policy that came from a foreign government that had provided him with money would make him an agent of a foreign power. US law requires citizens who lobby on behalf of a foreign power to declare themselves and the country they are working on behalf of to the Justice Department.

One former prosecutor who worked on the Mueller investigation said that if Kushner promised anything to MBZ and MBS in return for the money they offered him—even if it was just speaking to his father-in-law—he may have violated federal bribery laws, as well as the foreign agent statute. (Mr. Kushner’s lawyer denied that Kushner violated any laws while serving in the White House.) From PRINCES AND THIEVES: Jared Kushner and Mohamed bin Zayed’s Secret Plot to Remake the Middle East by Matthew Cole.