The United States and South Korea are rolling out a missile defence shield days after Pyongyang fired more test rockets, this time onto the Sea of Japan. Pyongyang’s angry and jittery over annual joint military exercises by Seoul and Washington. Nerves are particularly frayed because Pyongyang's not the only place that's hard to read these days. There's China and a US State Department that's gone mostly quiet since Donald Trump took office. What to make of the muted response from Washington?