Thae Yong-ho, a former senior official at North Korea’s embassy in London who defected in 2016, appeared before a congressional hearing on Wednesday to provide U.S. lawmakers with some perspective into the mindset of the North Korean populous, and into their enigmatic Supreme Leader, Kim Jong Un.

Tensions between North Korea and the United States have continued to escalate in recent months, as North Korea’s continued pursuit of nuclear weapons and increasingly advanced ballistic missile delivery systems has shifted the world’s perspective of the reclusive state from “all bark and no bite,” to a legitimate threat to the safety of America and its allies.  Since then, the United States and North Korea have exchanged aggressive rhetoric by way of headline-drawing statements from each nation’s respective leaders, but have done little in the way of establishing legitimate diplomatic channels.  In the minds of many, the two nations are on a collision course that ends in war.

That possibility was certainly on the minds of the House Foreign Affairs Committee as they spoke to the former North Korean official.  Open war with North Korea would likely not spill over the vast Pacific Ocean and onto American streets (unless Kim opted to launch a nuclear strike the U.S. and allies failed to intercept), but a real concern many have levied has been regarding the North’s artillery emplacements hidden throughout the mountains just north of the DMZ.  If war were to break out, many believe Kim would order the immediate shelling of South Korean population centers like Seoul, where 20 million people would be within his sights.

Those concerns were brought to Defense Secretary James Mattis’ direct attention by his South Korean counterpart, Defense Minister Song Young-moo, during his visit to the DMZ last week.  On Wednesday, those concerns were further supported by Thae’s testimony.