Most states are of the view that military forces are needed and effective as means to reduce the risk of foreign attacks. They must note that some of today’s political and military realities are very different from those that existed up to the end of WWII. Border lines and land have lost some importance. The United Nations is a new factor but one that has not reduced the importance of national defence. Underestimating the need may be fatal, but exaggerating it means taking resources from more deserving needs. A table is offered of the military expenses of several states. Military budgets are currently (2023) sharply rising in many countries. The NATO alliance has set a minimum target of 2 % of GDP for national military budgets of their members. The US has long declared a policy of ‘all sector dominance’ and has by far the largest military budget. To deter the threat of nuclear and other non-conventional weapons raises intractable new issues. The three major nuclear weapon states seek to make sure that they will not ever lose the capacity to deter nuclear attacks by a second strike that would bring pain calculated to be unacceptable.