U.S. Secretary of Defense Mark Esper is crisscrossing the Asia-Pacific region on his first international trip as head of the Defense Department. The trip began as the U.S. withdrew from a decades-old arms control pact with Russia, the Intermediate-Range Nuclear Forces Treaty. The withdrawal means Washington and Moscow are free to develop ground-based missiles with a range of 500-5,500km. And that could be bad news for a country that was never even part of the pact--China. Our VOA Pentagon correspondent Carla Babb is traveling with Esper and explains why.