On Friday, the website of NPR posted a satellite image that the public broadcaster said showed intense activity around the North's Sanumdong site, where missiles and satellite-launching rockets have previously been assembled.
"We've seen a lot in North Korea", he said.
"They never seem to get around to it, though", he said.
He said Mr Trump had proposed a "big deal" in the Hanoi summit under which North Korea would completely denuclearise and also give up its chemical and biological weapons.
Two days after Mr Kim's summit with US President Donald Trump broke down over sanctions relief and disarmament steps last month, satellite images showed that North Korea was rebuilding a long-range rocket site it recently dismantled. When Raddatz asked about Trump's comment that he would be surprised if Kim Jong-un did anything that was not consistent with their understanding, Bolton acknowledged that he would not react the same way.
As North Korea appears to be preparing for a potential missile launch, a report from the Los Angeles Times reports that the North Korean regime is simultaneously lobbying for increased humanitarian aid through the United Nations, for assistance with a food shortage in the country.
Kim, however, has honored an informal freeze on nuclear and missile testing announced last April. He said the Hanoi summit showed how "difficult" and "painful" it will be to achieve denuclearization and peace on the Korean Peninsula.
"The technology for making sure you put the satellite into the right orbit is the same technology for making sure the missile is on the right course", Dr Lewis said, noting that previous North Korean space launches used older technology.
-North Korea diplomacy. "I wonder if North Korea should avoid" such an action, Moon said in a panel discussion.
"I would be very, very disappointed in Chairman Kim", Trump said on Wednesday.
Trump, who once warned Pyongyang of "fire and fury" if it threatened the United States, has been trying to negotiate the North's denuclearization with its leader Kim Jong Un, but their recent Hanoi summit ended in failure. But the meeting collapsed over an impasse over how many weapons sites North Korea would shut down and the extent of economic sanctions relief the USA would offer in return.