The sad reality is that diplomacy and the dictates of foreign policy can require relationships with the most unpleasant of allies, and few relationships have been more indicative of this than the United States' long association with Saudi Arabia.

It is hard to imagine two countries with less in common, at least from the perspective of ideals. The United States stands for freedom of expression, of religion, its leaders elected by and answerable to the people, its laws applying equally to all.

Saudi Arabia will not tolerate any expression that falls outside the strict religious and political dogma prescribed by its monarchy. Its leadership selectively condemns some terrorism with one voice, while using its extreme oil wealth to back terrorists who serve its interests. The House of Saud, the ruling family with thousands of members, is secure in its life of privilege.

But as with all presidents before him dating to Franklin D. Roosevelt, President Obama is restrained in any criticism of the Saudi nation and focuses instead on common interests. This week the president traveled to Saudi Arabia to pay his respects following the death of King Abdullah and to meet with this successor, King Salman.

Questioned about showing such deference to a regime with an abysmal record on human rights, President Obama provided a pragmatic response.

"Sometimes we have to balance our need to speak to them about human rights issues with immediate concerns that we have in terms of countering terrorism or dealing with the regional stability," the president told CNN's Fareed Zakaria.

There is no denying the strategic advantages of the relationship, particularly in bolstering Sunni Saudi Arabia as a counterbalance to Shiite Iran, with its nuclear weapons program and aspirations of regional dominance.

Under King Abdullah, the Saudi nation supported U.S. efforts to stop the advance of ISIS. It has long supported U.S. efforts to broker a peace agreement between Israel and the Palestinians. And the former king at least made some effort to embrace modernity and create opportunities for women, though the changes have been glacial.

Most fundamentally, it is a relationship grounded in the politics of oil. That dynamic began during World War II when the Saudis needed military assistance, the U.S. oil for its war effort.

The U.S. economy grew dependent on foreign oil. Saudi Arabia, with its massive oil reserves and leading role in OPEC, helped set the price point for that oil. And with its oil revenues, it became a major purchaser of American weapons.

The U.S. and its successive presidents have had to overlook a lot. Fifteen of the 19 hijackers on Sept. 11 were Saudis and potential ties to the ruling family were never adequately explored. The ideological DNA found in many of the terrorist groups in the Muslim world can be traced to the harshly intolerant form of Islamism demanded by the House of Saud.

Only recently, Saudi courts ordered a 10-year prison sentence and 1,000 lashes with a cane for Raif Badawi. His crime was offering an online forum where people could discuss religious and political matters. Mr. Badawi was found guilty of "insulting Islam" and "going beyond the realm of obedience."

No hint of opposition is tolerated - one reason there was no "Arab Spring" in Saudi Arabia.

The Independent, a British national morning newspaper, reported 182 public executions in Saudi Arabia last year, at least 12 of them women, sentenced after Islamic trials with opportunity for defense or mitigating circumstances, such as mental illness. A popular form of execution is beheading. Sound familiar?

With increased domestic U.S. oil production, OPEC has lost the sway it once enjoyed and so, to a degree, has Saudi Arabia. It is time for the United States to take a more forceful approach in condemning the human rights record of its longtime ally and demanding that it tone back its clandestine support of terrorist groups. That, at least, might make this relationship based on common interests a bit less unpleasant.