North Korea's Kim Jong-un makes surprise visit to China via newly opened bridge

NEW: North Korea's Kim Jong-un makes a surprise visit to China, crossing via a newly opened bridge.

Kim Jong-un just crossed into China, unannounced, over a bridge that only just opened.

North Korea's leader does not do casual trips. Every time he leaves Pyongyang it's choreographed down to the minute, so a surprise crossing into China is a signal in itself. And the route matters too, a newly opened bridge on the border, which tells you Beijing and Pyongyang wanted this seen as something fresh, not the same old train ride.

The man he's almost certainly going to see is Xi Jinping, and the timing is what I'd watch. Washington is rattling sabres at Iran and Cuba in the same week, and here's Kim walking into the arms of his biggest backer. China is North Korea's economic lifeline, nearly all of its trade runs through that border.

When Kim moves, it's because something's been agreed in advance. The question is what he's carrying home.

This is Liu Yang, reporting for HIT.