Saudi Arabia has been a strategic US partner in the Middle East for decades, first as a bulwark against the expansion of USSR-friendly regimes during the Cold War, then as an important guarantor of oil sector stability. Successive US administrations have paid special attention to maintaining strong relations with Riyadh. In fact, since the 1973 oil crisis, every US president, with the exception of Ronald Reagan, has paid a personal visit to the kingdom.

US President Donald Trump was the first to choose Riyadh as the destination of his first official state visit, underscoring the importance of US-Saudi relations to his administration. But since his visit in May 2017, Trump has very much departed from Washington’s traditional approach to relations with Saudi Arabia. Despite his repeated claims that he is deriving maximum benefit for the US from his engagement with the Saudi leadership, he has, in fact, gravely mishandled ties with Riyadh.

Over the past year and a half, Trump – with the help of his adviser and son-in-law Jared Kushner – has formed increasingly personalised relations with the kingdom. As a result, the focus of US foreign policy towards Saudi Arabia has switched from the traditional pillars of its strategic partnership to backing for one member of the royal family and his political ambition – Crown Prince Mohammed bin Salman (MBS).

This approach not only threatens to compromise US interests in Saudi Arabia but has also led to a slew of disasters, the latest of which is the brutal murder of journalist Jamal Khashoggi in the Saudi consulate in Istanbul.

Historical ties and royal rivalries

US-Saudi relations date back to the 1930s when US energy companies discovered oil in the Arabian Peninsula and pushed their government to engage with the Saudi ruler and secure their interests. In 1945, the founder of modern-day Saudi Arabia, King Abdul Aziz Ibn Saud and President Franklin Roosevelt met on the board of the US destroyer Quincy.

During the meeting, the leaders laid the foundations of the enduring strategic relationship between the two countries: Washington was to ensure Riyadh’s security in return for a Saudi guarantee of US access to its oil reserves.

Since then, this arrangement has been maintained by six kings and 12 US administrations. For Washington, the relationship was grounded in an institutionalised long-term strategy rather than personal ties between individuals and short-term economic gains.

For this reason, the US has consistently steered away from the frequent rivalries within the royal court. In 1953 when the death of Ibn Saud plunged the royal family into a power struggle between his sons Saud, who was crowned king, and Faisal, who became the crown prince, Washington did not intervene. Throughout the ten-year struggle between the two, US Presidents Dwight Eisenhower and then John F Kennedy were more concerned about ensuring the stability of the House of Saud than about choosing sides.

Over the next few decades, this approach strengthened the relationship between Washington and Riyadh, which enabled it to withstand major political quakes, such as the oil crisis in 1973, the Iranian revolution, the Iraqi invasion of Kuwait, the 9/11 attacks, the Arab Spring, and the Iranian nuclear agreement.

These crises were never linked to one Saudi king or prominent member of the royal court, nor were they the result of personal favour that anyone in Riyadh curried with a US president. Even as personal relations soured, as in the case of President Barack Obama, whom the Saudis resented for his position on Iran and the Arab Spring, the strategic relations between the two countries did not suffer. In fact, it was during the Obama administration that Saudi Arabia received some $118bn-worth of US-made weapons.

Personalising relations with Riyadh

But Trump brought a new dynamic into bilateral relations with Saudi Arabia. His electoral victory in 2016 came amid another power struggle within the royal court – one led by the ambitious son of King Salman, Mohammed. Ever since the first visit by MBS to Washington in March 2017 and the subsequent official POTUS trip to Riyadh two months later, relations between Saudi and the US have increasingly borne signs of personal presidential favouritism towards the young crown prince.

Trump’s backing for MBS emboldened the crown prince to undertake a number of disastrous political moves. And against the advice of various government agencies and administration representatives, the US president has expressed personal support for most of them, mostly on Twitter. Trump appeared to support the Saudi-led blockade on Qatar in June 2017, and later endorsed the round-up and shake-down of princes, ministers, and businessmen in the Ritz Carlton Hotel.

He praised the crown prince’s Vision 2030 programme but was silent on the aggressive personalisation of political and economic power he has pursued. He applauded the lifting of the driving ban for Saudi women but failed to condemn the detention of women’s rights advocates. He has bragged about concluding billions-worth of deals with Riyadh while staying silent on war crimes committed by the Saudi forces in the disastrous Yemen war, which was launched under MBS’s leadership in 2015.

In all this, Trump has allowed his son-in-law, Kushner, to take a lead role in diplomatic contacts with Saudi Arabia, which are increasingly looking like a family affair. The close relations between Kushner and MBS and revelations that the Saudi crown prince had bragged about having Trump’s son-in-law in “his pocket”, have caused growing concern within the State Department, Department of Defense and intelligence agencies. Relying on personal relations rather than official diplomatic and political channels is highly risky, especially if information about these contacts stays private and the wrong political signals are relayed.

Trump’s problematic approach to managing relations with Saudi Arabia has encouraged MBS’s reckless behaviour. The current political storm surrounding the murder of Jamal Khashoggi is the direct result of Trump’s mishandling of the Saudi portfolio. If the US president does not change his approach, he risks damaging the decades-old strategic partnership between the two countries and enabling more political disasters in Saudi Arabia which could destabilise the country and threaten US interests.

The fallout of the Khashoggi tragedy presents an opportunity for the Trump administration to correct its course and return to Washington’s traditional approach to Saudi Arabia. If Trump does not sever his personal ties to MBS, the consequences could be grave.

The views expressed in this article are the author’s own and do not necessarily reflect Al Jazeera’s editorial stance.