Transcript for North Korea's attempted missile launch explodes immediately after liftoff

Hello, from Seoul, south Korea. It's evening here in the city of 10 million people. On high alert in a week end of escalating tensions. Hours ago, yet another north Korean missile launch. The fifth of 2017. This time, it blew up seconds after leaving the launch pad. U.S. Officials believe it was likely a medium-range ballistic missile, the kind we have seen before. Still, the latest launch rattled nerves, especially after the Sunday appearance Saturday of what could be new long-range weapons at North Korea's big anniversary parade. Canisters that appear large enough to house a missile capable of hitting the united States. You can see them there rolling past north Korean leader Kim Jong-un. Green camo on huge transporters. If he, indeed, has a missile big enough to reach the united States, and if he can make a war head small enough to fit on it, will the U.S. Be forced the respond. This hour, all the angles on the most important sportstory if tn the world right now. Are the new missiles we saw at Saturday's parade real? Does Donald Trump have a firm red line? Is there room for negotiation or are trump and Kim on a collision course? Vice president Mike pence arrived here in Seoul today, the start of a ten-day Asia tour. With China warning both sides to cool it, North Korea is at the top of the agenda. In a moment, we'll talk to trump security adviser H.R. Mcmaster. He's in Afghanistan, where the United States just proved what it can do with a mother of all bomb strikes on ISIS, a dramatic show of American fire power.

This transcript has been automatically generated and may not be 100% accurate.