Military spending boosts the GDP

Military spending boosts the GDP. GDP is Government spending + Private Consumption + Gross Investment + Exports - Imports.

 By increasing military spending, you are increasing government spending, and thus increasing the GDP. If Military spending was cut, the GDP fall. The reason people want to see a reduction in military spending has nothing to do with GDP. It has to do with debt. Because all spending to boost the GDP leads to debt. The government doesnt have the money to increase military spending. Thus it must borrow money in order to increase military spending. The private sector doesnt have the money to boost the private spending, thus it needs to borrow money to boost the private spending.

 So if the economy is at 10 dollars. And the goal is to increase the economy by 10 percent. Then an additional 1 dollar needs to be borrowed to bring the GDP to 11 dollars thus leading to a ten percent increase in GDP. And at the same time adding an additional dollar to the nation's debt. In short, liquidating the military would not help improve the national economy, but it would alleviate the national debt. This is because the country doesnt have the money pay for the military. It doesnt even have the money to pay for civilian goods and services. This deficit must be paid for by borrowing.