4 myths about war, according to Trump's next top military adviser

Americans' belief in technology encourages this myth. At its heart is that wars can be won from afar, without getting troops on the ground. Whether it is the strategic bombing during World War II or launching cruise missiles, there are those who believe that will be enough to defeat an enemy.

"These allow you to shape battlefields and set the conditions for battle, but the probability of getting a decisive outcome in a war from launching missiles from afar has yet to be proven in history," Milley said.

This is the idea that it is possible to quickly generate forces in the event of need.

In World War I, it took more than a year for American forces to make a significant contribution on the battlefields of France after the United States declared war in April 1917. In World War II, the US Army fought on a shoestring for the first year.

War has only become more complicated since then, Milley said, and it will take even longer for forces to generate. "I think for us to maintain strength and keep national credibility, we need a sizable ground force, and I have advocated for that," he said.

"Armies or navies or air forces don't go to war. Nations go to war," Milley said.