The U.S. has been at nearly perpetual war with other states, or itself, since its inception. The day that we can no longer afford to cause more wars overseas will be the day that we turn on one another and implode. The U.S. is, by political definition, a warring state.
Foreign campaigns are essential to U.S. survival because they provide the body politic with outlets for aggressive discourse. Like any intelligent government, war is the means to keep the public satiated and distracted from any injustices that happen domestically.
The number of restrictions on their freedoms that Americans are willing to abide in this century are partially a result of distractive wars. The day that there are not wars to fight, the people will see exactly what has been done to them and there will be an uprising.