US SB1583

Prohibits U.S. assessed contributions to the United Nations from being used to fund the African Union Support and Stabilisation Mission in Somalia (AUSSOM) or any African Union-led peace support mission in Somalia under UN Security Council Resolution 2719 (2023)

Directs the U.S. Ambassador to the UN to oppose and decline to join consensus on any Security Council resolution authorizing such prohibited funding

Exempts from the prohibition: funding for the UN Support Office in Somalia (UNSOS), voluntary U.S. contributions expressly appropriated by Congress for AUSSOM, humanitarian assistance through NGOs or UN agencies operating independently of AUSSOM, and U.S. personnel costs for oversight

Requires the Secretary of State to conduct annual assessments of the African Union's ability to meet Resolution 2719 conditions and submit reports to Congress within 90 days of enactment including AUSSOM performance analysis, financial breakdowns from international contributors, and progress on alternative funding mechanisms

Amends the United Nations Participation Act of 1945 to extend congressional consultation requirements to African Union peace support operations receiving UN assessed contributions under Resolution 2719