Evidence is growing that North Korea is refusing to wind down its ballistic missile program and even appears to be adding sites while failing to report them.

As part of the framework agreed to between President Trump and North Korean dictator Kim Jong -Un in June, North Korea was supposed to pursue the dismantling of its nuclear program and its ballistic missiles.

Earlier evidence showed North Korea not following through on the commitment and now the Center for Strategic and International Studies says North Korea is operating mobile missile bases close to the South Korean border.

North Korea expert Gordon Chang, author of "Nuclear Showdown: North Korea Takes on the World," says the revelations are not all that new but the involvement of the mobile missiles is very disturbing.

"It's the mobile missiles that can hide before launching that we're really concerned about," said Chang.

"We'd have maybe only an hour's notice, and that should be sufficient time to find and destroy a mobile missile that is about to be launched, but in a wartime situation we may not be able to do that," added Chang.

Chang says Trump should have already re-imposed sanctions against North Korea and slapped others on China and Russia for flouting sanctions to help North Korea continue its nuclear and missile programs.

Chang worries Trump is too personally invested in the narrative that he was able to solve the North Korean threat, but he believes the evidence will soon be overwhelming.  He sees Trump's about-face on China on trade as an encouraging precedent.

"I think he could very well do the same thing to Kim Jong-Un, especially if he feels that he's been embarrassed and humiliated by the North Korean leader.

"At this point, I think we can say there's an 'emperor has no clothes" moment.  So President Trump does need to pivot to a much more severe, harsh policy," said Chang.

Listen to the full podcast to hear Chang's explanation of how China has helped North Korea cheat on its missile program and how the world is likely to react if Trump does bring back sanctions.