That has angered North Korea, whose foreign minister said in September the North had "every right" to take countermeasures, including shooting down the U.S. warplanes, though many experts doubt it has the actual intent or ability to do so.
Thae said Kim, who was educated in Switzerland, lacked the respect of North Korea's senior leadership after taking power in 2012 as the little-known, third son of his predecessor and father, Kim Jong Il.
He told reporters: "The two of us have also maintained a good working relationship and personal friendship".
Trump will visit five Asian nations in coming days for talks in which North Korea will be a major focus.
He said he was motivated by a desire to grant freedom to his children, who had already had a taste of the outside world in Britain.
While the "reign of terror" of North Korean leader Kim Jong-un can't be stopped, more can be done to disseminate outside information into the reclusive nation, he added.
North Koreans "don't care about state propaganda but increasingly watch illegally imported South Korean movies and dramas", weakening the regime's hold.
The Hwasong-12 lifts off from the launching pad at an undisclosed location near Pyongyang in August.
The Korea Peninsula was under the yoke of Imperial Japan from 1910 to 1945.
The United Nations (UN) responded to the test on Sept. 11 by imposing fresh sanctions on the rogue state.
Trump's trip comes amid escalating tensions with North Korea, which has continued to pursue its missile and nuclear programs and ramped up its missile testing.
President Trump doesn't intend to wait until that happens to quash North Korea's ambitions.
While the number is still concerning, it pales in comparison to Russia's estimated 7000 nuclear warheads, and America's 6800.
Stratfor, a US-based intelligence analysis company, noted in a report on Tuesday that the US Air Force also will send a dozen F-35A stealth fighter jets to a base in Japan in early November.
"What we are seeing from North Korea looks like some kind of stress in the ground..."
The site of the THAAD missile defense system in Sangju, North Gyeongsan Province.
Officials say that additional new improvements are underway to the hermit kingdom's nuclear fuel, missile launchers, guidance and targeting systems, forcing the US to recalculate the timing of the threat that a North Korean missile strike could pose to the US. During a recent visit by U.S. Defense Secretary Jim Mattis to Seoul, both Mattis and Song dismissed the idea of redeploying nuclear weapons.
He warned, however, that there are street protests in North Korea, 'there is no doubt that Kim Jong Un would stomp it out mercilessly with his forces, even tanks'. She said that preparations were under way for a bilateral summit at APEC, and that plans for President Moon Jae-in to visit China within the year were also in the works.
Kim Jong Nam died in February after two women rubbed his face with a liquid later identified as VX nerve agent as he passed through the airport in Kuala Lumpur.