The UN has begun its mission in Mali, taking control of around 6,000 West African troops.
The force will take over from French forces, which have controlled security operations in the country.
"This is not an anti-terrorist operation but of course the mandate has an element of real robustness in it and of course we are in a position to use all necessary means to defend ourselves and of course to defend the mandate," Herve Ladsous, the UN's head of peacekeeping, said on a visit to Timbuktu.
France will continue to keep troops on the ground, with around 3,000 soldiers to be deployed until the elections in July.
By December the UN force will have been expanded to 12,640 uniformed personnel.