The United States Department of Defense reports spending about $600 billion per year, which is more than one third of total military spending of all countries on the globe. The next biggest spender after the U.S. is China at about $200 billion per year.  A military defense system against foreign invasion is an obvious service that every state might provide, since this is not something that an individual can provide for him/herself.  Nevertheless, there are some who argue that maintaining a standing army in times of peace is not conducive to democracy or a  healthy economy.

A purely defensive strategy might include maintaining anti-ballistic missiles , as well as maintaining monitoring technology. The best defense may simply be self-reliance, food and energy independence, decentralized utility and communication systems, food supply chains and medical supply chains.  A strong defense includes a robust economy, in which wealth is not invested mainly in stocks and bonds, but invested in infrastructure, domestic manufacturing, food production, and private real estate.

A major alternative strategy for defense proposed by World Beyond War is to discontinue the practice of stockpiling weapons to increase one’s security by making one’s perceived enemies more secure. A non-provocative defense system would “re-configure training, logistics, doctrine, and weaponry so that a nation’s military is seen by its neighbors to be unsuitable for offense but clearly able to mount a credible defense of its borders. ”  In addition, citizens would be trained to thwart invasions, practicing resistance rather than mirroring the aggression of the invaders.