Morocco gained full independence in 1956, followed by Algeria in 1962. The uncertainty over much of the border alignment, and Morocco’s 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 civil war in the 1990s, relations once again soured, with Algeria closing the border in 1994. Relations thawed slightly with the advent of peace in Algeria in the early 2000s, though at present the border remains closed. Travel and trade between the two countries is allowed, but must be done either by air or sea.