What made the truth inconvenient was that avoiding catastrophic climate change would require people to live differently and maybe give up what they love (such as gas-guzzling cars).

For two months, we have all been living with another inconvenient truth, ever since Jamal Khashoggi, a Saudi journalist working for The Washington Post and living in the US, disappeared after entering Saudi Arabia’s consulate in Istanbul.

A large part of the truth is undeniable: Khashoggi was murdered by individuals with close ties to the Saudi government and its de facto leader, Crown Prince Mohammed bin Salman.

Weeks of official Saudi denials and lies only reinforced the conclusion — now also the reported judgment of the CIA — that the murder was premeditated and approved at the top.

MBS’s direct role may not be proven, but most observers familiar with Saudi Arabia harbour little doubt. It is not a system that tolerates freelancing.

What makes the truth inconvenient is Saudi Arabia’s strategic importance. The Kingdom accounts for over 10% of global oil output. Its sovereign wealth fund sits on an estimated $500bn.

Saudi Arabia is the most influential Sunni Arab country, occupying a special role within the Muslim world, as the custodian of Islam’s holiest sites. It is central to any policy confronting Iran.

Mohammed bin SalmanMBS, for all his faults, is a reformer, who understands that his country must open up and diversify, if it is to thrive and the royal family is to survive. He is also popular at home, especially with younger Saudis, who constitute the bulk of the population.

But the faults of the young and impulsive Crown Prince are many. In addition to his role in the murder of Khashoggi, he recklessly ordered the Saudi attack on Yemen, which triggered his country’s equivalent of the US war in Vietnam: a strategic and humanitarian catastrophe.

He kidnapped the Lebanese prime minister, undermined Qatar, arrested wealthy Saudis who refused to embrace his consolidation of power, froze diplomatic relations with Canada over a critical tweet, and imprisoned political activists, including women seeking greater rights.

The Saudi strategy for dealing with the outcry over Khashoggi’s murder is clear: Hunker down and weather the storm. Mohammed bin Salman and his inner circle are calculating that the world’s outrage will fade, given their country’s importance. He has good reason to believe that other Sunni Arab states will stand by him, because of the subsidies he provides.

Israel, too, has indicated support for MBS, owing to his willingness to normalise relations and, more important, because of the two countries’ shared interest in countering Iranian influence.

US president Donald Trump’s administration is standing by its man, so far refusing to acknowledge his role in Khashoggi’s murder and resisting calls for sanctions against Saudi Arabia.

What, then, should be done? Former US secretary of state James A. Baker recently drew a parallel to US policy toward China in 1989, at the time of the massacre of protesting students in Beijing’s Tiananmen Square.

George H.W. Bush’s administration (of which I was a part) worked hard to thread the needle: introducing sanctions to convey displeasure with the Chinese government, but limiting the punishment and keeping lines of communication open, due to China’s importance. Would a similar policy toward Saudi Arabia prove viable?

Ideally, the US and European governments would let it be known that they would be more open to working with Saudi Arabia if the power of the Crown Prince were reduced. There should also be limits on US arms sales and intelligence support, which, fortunately, the US Congress is likely to impose.

But more important than any sanction would be ratcheting up public and private pressure on Mohammed bin Salman, regarding what is needed and what needs to be avoided. What is needed is a concerted push to end the Yemen conflict.

What needs to be avoided is exploitation of the Trump administration’s anti-Iran animus to provoke an armed confrontation that would force others to overcome their qualms and side with Saudi Arabia.

A war with Iran would be costly and dangerous. MBS should be made to understand that the US will be a strategic partner for Saudi Arabia only if he acts with greater restraint in Yemen and elsewhere, and with greater respect for US interests.

Consultations should also be held with China and Russia. Unlike the US, both have working relationships with Saudi Arabia and Iran, which gives both a stake in preventing such a war.

All too often in the Middle East, a bad situation becomes a worse situation. MBS has created a bad situation. The aim should be to establish sufficient limits so that it does not become worse.

Richard N. Haass is president of the Council on Foreign Relations. His most recent book is A World in Disarray: American Foreign Policy and the Crisis of the Old Order.