It's no surprise that President Trump has downplayed the disappearance and alleged murder of Saudi journalist Jamal Khashoggi inside the Saudi Consulate in Istanbul nearly two weeks ago, despite the growing international scandal.

Never mind that the Turks say they've given U.S. officials tapes of the grisly torture and slaughter of Khashoggi, a U.S. resident and Washington Post columnist who was probably killed because he was a critic of  Saudi Crown Prince Mohammed bin Salman.

The president has continued to minimize the affair, saying Khashoggi was "not a U.S. citizen." In the face of bipartisan congressional outrage, he finally vowed "severe punishment" if the Saudis are found culpable.  But the Saudis won't stop lying without strong pressure from Trump.

>> READ MORE: Jamal Khashoggi affair highlights what happens when America abdicates role as free press defender | Trudy Rubin

The Khashoggi affair has morphed into something far larger than a gross violation of human rights and bedrock legal norms.  It has become a test of whether an American president is prepared to tolerate overseas assassinations of political opponents by strongmen whom Trump openly admires.

We know why the president refuses to criticize MBS (the nickname of the Saudi prince), who would have had to give the order for any such murder.  This prince is a buddy of First Son-in-law Jared Kushner and is the loose cannon upon whom Trump has based his entire Mideast policy, along with his boasts about $110 billion worth of arms sales (a gross exaggeration).

Yet the prince's recklessness has been evident since he was elevated by his father last year. Shortly afterward, he rounded up dozens of influential Saudis whom he kept prisoner for weeks in the Ritz-Carlton hotel in Riyadh in an apparent shakedown.  Right after the roundup Trump tweeted that he had "great confidence in …the Crown Prince of Saudi Arabia" and his father, King Sultan, "who know exactly what they are doing."

>> READ MORE: Trump is suffering from a bad case of autocrat envy | Trudy Rubin

Since then MBS has made a series of foreign-policy blunders that undercut U.S. policy: enmeshing the kingdom (with reluctant U.S. help) in a quagmire war in Yemen, failing to help curb Iranian expansion in Syria, disappointing Kushner's naïve hopes of godfathering a Mideast peace deal.

And despite expanding the rights of women, and clumsily attempting economic reforms, MBS has also jailed several pioneering female activists. Yet the praise from the White House flowed on.

So it's no surprise that MBS might feel he could act with impunity — sending two planes and a 15-man hit team to Istanbul, according to the Turks, in order to kidnap or kill Khashoggi inside the Saudi Consulate.

Of course, there's another factor that may have led the prince to believe he could act with impunity.  Trump has been indifferent toward overseas assassinations of opponents by other autocrats he admires.

The case of the poisoning of the former Russian double agent Sergei Skripal in Britain by Russian military intelligence agents is a vivid example.  In the face of detailed and damning evidence, Vladimir Putin denies any Russian involvement.  Just as the Saudis are doing in the face of irrefutable evidence of what happened in Istanbul.

When Western leaders asked for Trump's help in March in organizing a united response to the Skripal affair, the president was extremely reluctant, as detailed in Greg Miller's new book, The Apprentice.  When British Prime Minister Theresa May told Trump by phone that British authorities were 95 percent sure that Moscow was responsible, Trump replied: "Maybe we should get to 98 percent."

Trump had to be dragooned by staff into acquiescing to the expulsion of dozens of Russian operatives in retaliation for the poison attacks, and even then was furious at having to do so.  And, of course, Trump has repeatedly defended Putin when asked about the murders of 28 journalists on Russian soil.

The message sent by such U.S. foot-dragging has global repercussions: Trump was less disturbed by Kremlin assassinations of opponents than having to upset the Russian leader he admires.  So why should other favored autocrats worry?

And we mustn't forget the assassination, on Kim Jong Un's orders, of his exiled half-brother at a Malaysian airport; the killers smeared the victim's face with the rare VX nerve agent.  This episode appears to have faded from popular memory amidst the current lovefest between Trump and the North Korean leader since a Singapore summit that has yet to produce any moves toward eliminating North Korea's nuclear arsenal.   Yet Trump recently told a rally that he and Kim "fell in love" over "beautiful letters."

The fact that Kim used a nerve agent to murder abroad didn't undermine this lovefest (this column won't address the millions Kim has killed in camps or by starvation at home).

The point is not that U.S. presidents shouldn't talk with bad guys.  But lavish praise for those who kill opponents abroad puts a U.S. seal of approval to such crimes.

So if Trump permits the Saudis to stick to their big lie, hoping the Khashoggi affair will be forgotten, he encourages MBS to strike again. And he reaffirms the image of a U.S. president indifferent to assassinations ordered by autocrats he likes.

If this image is unfair, Trump needs to prove it soon.  For starters, cancel Treasury Secretary Steve Mnuchin's trip to the "Davos in the Desert" business conference to be held later this month in the same Ritz hotel where MBS's opponents were imprisoned.  Many business executives and news organizations are already pulling out.

And, if the Saudis continue to lie, it's time to consider sanctions, as a growing bipartisan chorus in Congress is demanding.  Otherwise, Trump might as well put out a sign on the White House that says, "Assassinations OK so long as arms sales on track."