The images, taken earlier this year, of the Sakkanmol missile operating base were released on Monday by the Beyond Parallel project, part of the Washington, D.C. -based think tank called the Center for Strategic and International Studies (CSIS).
Furthermore, North Korea has repeatedly rejected U.S. requests for a detailed and accurate disclosure of the country's nuclear and ballistic missile capabilities.
President Trump held a summit with North Korean dictator Kim Jong-un in Singapore on June 12, becoming the first US President to meet a North Korean leader.
The bases, which are located in "mountainous terrain, often spread out within narrow dead-end valleys", they write, could be used to deploy mobile missile launchers, which would be extremely hard for other nations to track and stop before the missiles could be fired. "I have talked with the administration and basically what we're looking at is they postponed it because they weren't ready".
Cha had been in line for appointment as USA ambassador to South Korea, but was dropped because of disagreement with the Trump administration's approach.
The US State Department commented on the issue, saying: "Should Chairman Kim follow through on his commitments, including complete denuclearisation and the elimination of ballistic missile programs, a much brighter future lies ahead for North Korea and its people".
For the time being, Pyongyang appears to sticking to a self-imposed moratorium on testing in return for a pause in U.S. military exercises with South Korea which Trump ordered after the Singapore summit.
Sakkanmol is one of 13 out of an estimated 20 undisclosed locations where North Korea continues to develop ballistic missiles, according to the report.
On Monday, state controlled media said that small-scale military drills by a few hundred U.S. marines and South Korean forces represented a violation of a summit agreement between Kim and the South Korean president, Moon Jae-in.
Trump also reassured critics that talks with North Korean leader Kim Jong Un were still occurring. The mushrooms were presented by Kim following a three-day summit in Pyongyang.
North Korea has said it has closed its Punggye-ri nuclear testing site and the Sohae missile engine test facility.
It came amid lingering doubts about whether the North will submit a full list of its nuclear and missile programs and engage in serious denuclearization talks in spite of Trump's all optimistic statements, including the talk of his good relationship with Kim.
Indeed, it appears to be adding to its stockpile: U.S. intelligence reports from the northern summer found that North Korea had begun producing new missiles at a factory, and Secretary of State Mike Pompeo acknowledged during Senate testimony that Pyongyang "continues to produce fissile material".
There have been several recent signs that diplomatic efforts between the United States and North Korea were stalling. Now it's North Korea's turn.
One of the destinations would be the Punggye-ri nuclear test site, where North Korean officials invited journalists to watch a partial demolition in September.
The report comes as talks between the U.S. and North Korea hit another snag last week, with a NY meeting between Secretary of State Michael Pompeo and the top negotiator from Pyongyang cancelled at the last minute.