Many find the president's statement curious indeed, given the seeming consensus among the Turkish and US intelligence communities that Saudi Crown Prince Mohammad bin Salman ordered Khashoggi's murder at the Saudi consulate in Istanbul.
But two simple numbers clarify just how much importance successive administrations, including Trump's, have placed on the US-Saudi relationship.
The first number is the number one.
Jamal Khashoggi was one man. He was a Saudi citizen, and considered an enemy of the state by "his" government to boot. He was neither a U.S. citizen, nor was he killed on U.S. soil.
In fact, he was technically killed on Saudi soil - consulates enjoy the same "sovereign" status as embassies. His murder, while evil and tragic, was really not any more the business of the U.S. government than the execution of an American in Texas would be Mohammed bin Salman's concern.
The second number is 2,977.
That's how many people 19 hijackers (15 of them Saudis) killed (excluding themselves) at the World Trade Center, at the Pentagon, and at a crash site in Pennsylvania on September 11, 2001.
No later than December of 2002, and presumably before that, the U.S. government knew that the 9/11 hijackers had received significant funding and support from Saudi government officials and members of the Saudi royal family.
That information remained classified until 2016, when 28 previously redacted pages from Congress's official 9/11 report were finally released to the public. And still "friendly" relations between Washington and Riyadh continued without interruption.
The U.S. invaded Afghanistan (none of the hijackers were Afghans) in response to the 9/11 attacks.
The U.S. government insinuated a relationship between al Qaeda and Saddam Hussein's regime in Iraq as part of its justification for invading that country in 2003 (none of the hijackers were Iraqis, and in fact al Qaeda was among Saddam's most implacable enemies).
But Saudi Arabia got a free pass, as did the United Arab Emirates (where two of the hijackers came from).
Why? Oil, money, and U.S. foreign policy.
Saudi Arabia and the UAE control a great deal of the world's oil, and can threaten to disrupt international oil markets (and international life in general) any time they don't get their way.
Saudi Arabia and the UAE are also the top two buyers of of US weapons.
Finally, Saudi Arabia and the UAE support the U.S. agenda of isolating Iran and frustrating its regime's regional ambitions, and allow the U.S. military to operate bases on their territory pursuant to that agenda.
Next to those considerations, 2,977 murders on U.S. soil, most of them Americans, didn't matter to George W. Bush or to Barack Obama.
Nor do those 2,977 murders, let alone the murder of one Saudi journalist in a Saudi consulate, matter to Donald Trump.
But they should.
Thomas L. Knapp is senior news analyst at the William Lloyd Garrison Center for Libertarian Advocacy Journalism.