But when it came time to actually punish Saudi Arabia's crown prince, America's strategic interests prevailed.

The Biden administration made clear on Friday it would forgo sanctions or any other major penalty against Saudi Crown Prince Mohammed bin Salman in the Khashoggi killing, even after a US intelligence report concluded the prince ordered the it.

The decision highlights how the real-time decisions of diplomacy often collide with the righteousness of the moral high ground.

And nowhere is this conundrum more stark than in the United States' complicated relationship with Saudi Arabia - the world's oil giant, a US arms customer and a counterbalance to Iran in the Middle East.

"It is undeniable that Saudi Arabia is a hugely influential country in the Arab world," State Department spokesman Ned Price said Monday when asked about Biden's retreat from his promise to isolate the Saudis over the killing.

Ultimately, Biden administration officials said, US interests in maintaining relations with Saudi Arabia forbid making a pariah of a young prince who may go on to rule the kingdom for decades.

That stands in stark contrast to Biden's campaign promise to make the kingdom "pay the price" for human rights abuses and "make them in fact the pariah that they are."

"We've talked about this in terms of a recalibration. It's not a rupture," Price said of the US-Saudi relationship.

But what the Biden administration is calling a "recalibration" of former President Donald Trump's warm relationship with Saudi royals looks a lot like the normal US stand before Trump: chiding on human rights abuses in the kingdom, but not allowing those concerns to interfere with relations with Saudi Arabia.

In recent days, Biden officials have responded to intense criticism of its failure to sanction the prince by pointing to US measures targeting his lower-ranking associates.

Those include steps against the prince's "Tiger squad" that allegedly has sought out dissidents abroad and sanctions and visa restrictions upon Saudi officials who directly participated in Khashoggi's slaying and dismemberment.

The language itself has softened, with Biden officials referring to Saudi Arabia as a strategic partner rather than pariah.

Watching it all, Trump suggested over the weekend that Biden's stand on Saudi Arabia's prince wasn't so different from his after all.

Khashoggi's killing by Mohammed bin Salman's security and intelligence officials was bad, Trump told Fox News, "but we have to look at it as an overall" situation. Biden seems to be "viewing it maybe in a similar fashion, very interesting, actually."

Mohammed bin Salman, 35, has consolidated power in Saudi Arabia since his father Salman, now 85 and ailing, became king in 2015.

The prince soon after launched a Saudi-led war in neighbouring Yemen that has deepened hunger and poverty in that country; opened a recently ended economic blockade of Qatar; and invited the leader of another Arab country, Lebanon, for a visit and without warning detained him.

The prince has silenced civil society at home, imprisoning writers, clerics, businesspeople and women's rights advocates, detaining and allegedly torturing fellow royals, and allegedly forming a squad charged with luring or abducting exiles back to the kingdom to face further punishment.

Khashoggi had fled Saudi Arabia and was deepening his criticism of the prince in columns written for The Washington Post.

When Khashoggi scheduled an October 2, 2018, appointment at the Saudi consulate in Istanbul to pick up paperwork needed for his wedding, Saudi security and intelligence officials were waiting for him there. So was Saudi security's forensics chief, known for his techniques for rapid dissections. Khashoggi's remains have never been found.

Senate Intelligence Chairman Mark Warner, a Virginia Democrat, told The Associated Press on Monday that he was open to more sanctions. But Warner, too, stressed that the United States needs to maintain the relationship with Saudi Arabia.

"This is a dangerous neighbourhood. And the Saudis are critical in terms of keeping pressure on Iran," Warner said.

Rights groups and the few Saudi dissidents in exile who still dare to speak say the United States is making a mistake.

They say Prince Mohammed's actions in his first five years in power show he's not bound by international norms or diplomatic persuasion. Waiving penalties on Mohammed bin Salman now also sends a signal to Saudis on the succession, when Salman dies, they say.

Forgoing punishment in such a brutal killing, of an internationally known journalist, sends a message of impunity for future slayings, not just for the prince but for all authoritarian governments, said Sarah Leah Whitson, leader of Democracy for the Arab World Now, a rights group Khashoggi founded not long before his death.

The Biden administration "basically sent the message that if you're at the top you're safe, and business will continue as usual, as long as we agree on some low-level officials to throw under the bus," Whitson said.

Australian Associated Press