As Commerce Secretary Gina Raimondo was visiting China earlier this week, a sea-green Chinese smartphone was quietly launched online.

It was no normal gadget. And its launch has sparked hushed concern in Washington that U.S. sanctions have failed to prevent China from making a key technological advance. Such a development would seem to fulfill warnings from U.S. chipmakers that sanctions wouldn’t stop China, but would spur it to redouble efforts to build alternatives to U.S. technology.