The military ruler of Niger, Gen Abdourahamane Tiani, is in Mali on his first international trip since getting power in July.
Niger’s neighbours – Mali and Burkina Faso – are also run by military leaders following coups since 2020.
The three countries have pledged solidarity in the face of international condemnation and sanctions.
They are also facing immense security challenges due to the presence of Islamist militants who carry out frequent attacks.
Gen Tiani has said Niger will return to civilian rule within three years.
Mali postponed a presidential election that was scheduled for early next year.