Substantial cut-backs in the national defence budget over the past five years have forced upon the Defence Ministry and missile designers alike a growing awareness of the importance of weapon costs. As a result, the ideal technical solution to a particular defence problem sometimes has to give way to the realism of what the country can afford to develop and procure—and, most important, what it could afford to sustain, if need be, in anger. A further factor has been the growing importance of exports to the country's economic position, to which arms make an important contribution. Weapon designs, therefore, have to be such that overseas customers can afford not only to purchase them but can also maintain and use them. This is particularly important in the case of developing countries.