And next we turn to north korea, the continuing threats of war today. The american secretary of defense called the threats, quote, a real and clear danger to the united states. Tonight abc's chief... See More
And next we turn to north korea, the continuing threats of war today. The american secretary of defense called the threats, quote, a real and clear danger to the united states. Tonight abc's chief global affairs correspondent martha raddatz is once again, in south korea, showing us how the united states is gearing up to respond if north korea is really intent on war. Reporter: Tonight, the u.S. Says it stands poised to respond. Some of the actions they've taken over the last few weeks present a real and clear danger. Reporter: At the border, we were there with the u.S. Troops on high alert. Then, there is the missile battery being sent to guam, and the two guided msile destroyers -- eyes and ears -- scanning for the very first moves by the north. And warplanes, including fighter jets, u-2 spy planes and a-10 attack jets in the skies today, part of a massive military exercise overseen by a u.S. Lieutenant general who brought in f-22 stealth fighters as well. They'd be first into the north if war broke out. Their super cruise capability, their stealth capability gives them the opportunity to go places no other aircraft can go. Reporter: In the secretive north stands the largest special operations force in the world, the head of the spear of the world's fourth largest military but all that military and the nuclear weapons program has come at a very high price. This checkpoint is surrounded by north korea on three sides. It's easy to tell where north korea begins. It's the place with no trees. The people chop them down for firewood to keep warm and eat the softer roots. The lack of food and nutrition is so bad in north korea that unicef estimates 28% of the en have stunted growth. One study finding, on average, north koreans are a full two inches shorter than south koreans. Despite north korea's formidable military power, the u.S. Is certain that would eventually be crushed in any type of war by the u.S. And south korea. But north korea could, no doubt, inflict substantial damage if there was a surprise attack.
This transcript has been automatically generated and may not be 100% accurate.