Since world war 2, united states has never used its military to the full power. Army was used in vietnam and korean war, but none of it triggered a national crisis where almost all soldiers were working. And now, in the current age, nuclear weapons already dominate the world. Nuclear weapons are one of the reasons there has been no global conflict after world war 2, because any country knows starting a global war would result in a nuclear war with no winner and humans as the loser. An army is needed, but the current scale is not sustainable, there is 40 trillion dollars of bedt to pay, keeping that number growing just creates a bigger challenge for future generations. And for countries like China and Russia, it is extremelly unlikely they will have a full scale war with united states, and if that really hapneend, nuclear bombs are the only thing that matter.
Keeping a small army and a few nuclear weapons is needed for security, putting 1.5 trillion into army when the country is already in debt is a bad economic decision