China warns it will not "sit idly by" while the US moves to put new strike missiles on its "doorstep"

Mark Esper, the new US secretary of defense, told reporters over the weekend that he is interested in fielding intermediate-range missiles in Asia "sooner rather than later."

Fielding this capability in the Pacific, which the US is looking at in the wake of the INF Treaty's collapse, would allow the US to confront China in new ways.

"We want China's leadership to wake up every morning and think this is not a good day to pick a fight with the United States or its allies," a missile defense expert told INSIDER, commenting on Esper's remarks.

China warned Monday that it "will not just sit idly by and watch our interests being compromised," nor will it allow another country to "stir up troubles at our doorstep."