 Complete the following phrase:  Morocco gained full independence in 1956, followed by Algeria in 1962. The uncertainty over much of the border alignment, and Moroccos claims for a so-called Greater Morocco encompassing much of north-west Africa, led to the Sand War of 1962-3. Various agreements were signed in 1969-70 aiming to provide a peaceful resolution of the dispute, which resulted in the treaty of 15 June 1972 which demarcated for the first time the entire boundary. However relations worsened when Spain announced its intention to pull out of Spanish Sahara modern Western Sahara in 1975, with Morocco then annexing the northern two-thirds, and later the whole, of the territory. Algeria opposed the annexation and provided shelter for the Polisario Front Saharawi nationalist militia and Saharawi refugees on its territory. As Algeria slid into 