Washington and Baghdad agreed last year that the international coalition against IS -- established in 2014 to help local forces retake territory seized by the jihadists in Iraq and neighboring Syria -- would end its military mission in Iraq by the end of September 2025.

"This reduction reflects our combined success in fighting ISIS and marks an effort to transition to a lasting US-Iraq security partnership," Pentagon spokesman Sean Parnell said in a statement, using an acronym for IS.

"The US government will continue close coordination with the government of Iraq and coalition members to ensure a responsible transition," Parnell added.

The coalition will continue its military operations in Syria, with international troops permitted to support anti-IS operations there from Iraq's autonomous Kurdistan region through September 2026.

Parnell separately announced in April that the United States would roughly halve the number of troops it has deployed in Syria to less than 1,000.

IS has suffered major defeats in both Iraq and Syria, but the jihadists still have some fighters in the countryside of both countries, and US forces have carried out periodic strikes and raids to help prevent the group's resurgence.