In a new attempt to ensure that the American-led force in Somalia disarms rival militias and pacifies the whole country, Secretary General Boutros Boutros-Ghali says he plans to release a letter he sent President Bush setting out the understanding he thought he had reached with the administration on the American role in the operation.

The United Nations chief said he wrote to Bush immediately after the Security Council voted on Dec. 3 to authorize the United States to send troops to Somalia to get food to starving Somalis. He said he had explained the private commitment he thought the administration had given him to disarm the rival gangs.In an interview Friday evening, Boutros-Ghali said the Security Council had agreed at American urging not to spell out these commitments in the mandate it gave the U.S. forces, merely saying the troops should create a "secure environment for humanitarian relief operations in Somalia."

But he maintained that the United States had discreetly promised to disarm the warring factions. "Without that letter (to Bush), I believe my report would have no value," he said.

Over the past few days, senior U.N. officials and the United States appear to have developed differing concepts of the role of the American force in Somalia.

While officials in Washington seem to envision a short-lived operation primarily aimed at getting food to the starving, the United Nations wants the U.S.-led forces to undertake the more difficult and dangerous task of systematically disarming the Somalis, arguing that until this is done it cannot make a serious effort to promote political reconciliation.