The US defence budget covers various expenses, including military personnel salaries and benefits, procurement of weapons systems and equipment, research and development of new technologies, military construction projects, and operation and maintenance costs. A significant portion of the budget goes towards the maintenance of the country's nuclear arsenal and the operation of overseas military bases.
It's worth noting that defence spending in the United States is subject to annual budget negotiations and can vary from year to year. The amount allocated for defence can be influenced by geopolitical factors, global threats, and domestic priorities.