The announcement also came a few days after a bipartisan group in Congress introduced a resolution condemning Mr. Kony and supporting a regional military effort from the four most victimized nations. The armies of those nations — Uganda, South Sudan, Central African Republic, and Democratic Republic of the Congo — have been fighting the L.R.A. since last year under a loosely organized effort. But some soldiers in those armies have resentments toward one another that have overshadowed their common goal of eradicating Mr. Kony’s group and arresting him.

The new operation announced Friday could offer a new beginning.

Uganda said it would reallocate 1,500 of its troops currently fighting the L.R.A. in the Central African Republic under the new African Union operation, to be headed by Uganda, but it remained unclear how new troops would be brought in from the other nations, when they would arrive, and whether they would all be under a single military command.

Headquarters for the operation will be in South Sudan, the world’s youngest and possibly most cash-hungry nation, and will include offices and administration.

The United States, which has participated in special operations against the rebel group in the past, last year sent 100 troops to Uganda and operational field locations to act a special advisers to the national forces, and reiterated its support on Friday for the regional military operation and its own “multi-year strategy.”

The African Union said Friday that its operation had been months in the planning, and would not stop until Mr. Kony was captured.