The United States is preparing to withdraw nearly all of the military troops deployed to West Africa to help with the response to the Ebola outbreak.

The White House says the U.S. and other nations have made substantial progress in fighting Ebola in West Africa and says the response is entering a new phase.

Of the 2,800 troops that were deployed, the U.S. plans to leave just 100 in place after April 30. About 1,500 of those troops have already returned.

The White House says many of the functions the military has been handling will now be performed by civilians.

President Barack Obama was to announce the withdrawal on Wednesday at an event at the White House. He was also to outline next steps the U.S. plans to take.