As he concludes a visit to East Asia on Monday, Secretary of State Mike Pompeo should take a detour on his way back to Washington, through Riyadh, Saudi Arabia.

Pompeo needs to meet with Crown Prince Mohammed bin Salman and find out what just happened to Jamal Khashoggi. A Saudi critic of the crown prince, Khashoggi went missing last Tuesday as he visited the Saudi consulate in Istanbul, Turkey. More concerning, Turkish authorities now say they have "concrete proof" that Saudi Arabia murdered Khashoggi. That proof is likely based on either Turkish informants inside the consulate or from Turkish intelligence intercepts of Saudi communications. The Turkish NIO intelligence agency heavily resources its Saudi-focus operations, so it likely has a good idea of what occurred.

Yet the person who knows best what happened to Khashoggi is the de facto Saudi ruler, Crown Prince Mohammed. Pompeo should meet with the crown prince and ask him whether his officers have either killed Khashoggi or kidnapped him. If the former is true, the U.S. should publicly condemn Riyadh's behavior and make clear to the crown prince that future such incidents will negatively affect U.S. policy on Saudi Arabia. If the latter is true, the U.S. should pressure Crown Prince Mohammed to release his prisoner. Because Saudi Arabia is seen as a very close U.S. partner, its actions on human rights issues also envelop America.

Yet the U.S. must chart a cautious path here. Pompeo should meet the crown prince in private and not make this situation more of a spectacle than it already is. While aggressive towards his domestic and foreign critics, and sometimes highly unpredictable, Crown Prince Mohammed supports counter-terrorism efforts and is an otherwise constructive U.S. partner. Moreover, the U.S. has great interest in the success of his reforms to empower Saudi women and to diversify the Saudi economy.

Those reforms will be crucial in fostering a greater sense of opportunity for Saudi Arabia's young population. Without that opportunity, young Saudis will become a wellspring for terrorist recruitment. At the same time, if the U.S. pressures Crown Prince Mohammed too hard, he may reorientate his regime more favorably toward Russia — which has no concern for human rights issues.

The first priority is to find out what the Saudis have done and why. While Pompeo probably already knows, thanks to U.S. intelligence, he must get the crown prince's personal explanation. Then President Trump can respond.