The U.S. is pledging up to $60 million to help a 5,000-troop African force get going on fighting extremists in western Africa's vast Sahel region.

U.N. Ambassador Nikki Haley announced the planned contribution Monday as the Security Council discussed the joint force being launched by Mali, Burkina Faso, Mauritania, Niger and Chad. U.S. Secretary of State Rex Tillerson also issued a statement from Washington.

The so-called Group of Five countries agreed in February to assemble the force to combat extremist groups, organized crime and human trafficking. The nations have been grappling with extremists linked to the Islamic State group, Boko Haram and al-Qaida's North Africa branch.

In June, the European Union announced a 50 million euro ($58.1 million) contribution. The joint force's first-year budget is 423 million euros ($492 million).