As "T. Rex" Tillerson knows, there's a lot more in play than glib-talking Larry gets:

Putin's version of "Make Russia Great Again" depends critically on oil revenues, and while Russia is one of the world's biggest producers, current production from its mature fields is not sustainable. T. Rex got to know Putin from his Exxon days, for which Russia needed and continues to need American expertise and capital to develop resources such as the massive Bazhenov field.

Let's look at this another way. Venezuela has the world's largest proven oil reserves, and yet its people are rummaging through dumpsters and suffering malnutrition, amid social breakdown. No one is going to invest while Maduro and his henchmen remain in power.

For Russia to become a pariah means a return to the Iron Curtain days for its oil sector, and further constraints on the wealth of Putin's oligarch friends. Against all of this, Assad is disposable, and there is no shortage of terrorists for plausible deniability.