In the wake of major natural disasters outside help is often needed. Thus the Royal Palaces of Abomey in Benin were simultaneously inscribed on the World Heritage List and the List of World Heritage in Danger in 1985, at the request of the government of Benin itself, after a tornado struck the site causing extensive damage. Since then, its restoration has been an ongoing project involving experts and institutions from a number of countries around the world. While the destruction wrought by tornadoes and cyclones is swift and brutal, other natural phenomena wreak havoc in slow motion. Timbuktu in Mali, for instance, is threatened by the gradual encroachment by desert sands and international assistance has been required to consolidate the three great mosques of the city.
Mining operations can also threaten to compromise the values of certain sites.
In the former case, concessions were granted in areas which had originally been included in the Reserve, while in the latter mining was being planned in an area which, while outside the perimeter of the Park, could have led to the pollution of the waters of the Park with off-flow from the mine. Successful restoration Armed conflict is a major threat to some sites. Several sites however, damaged in this way, have been successfully restored thanks to their inscription on the List of World Heritage in Danger. In November and December 1991, when seriously damaged by artillery fire, the city was immediately included in the List of World Heritage in Danger. As a result, in December 1998 it became possible to remove the city from the List of World Heritage in Danger.