UNITED NATIONS — Many U.N. officials feel dismayed and perplexed by the vacillating American policy on Somalia: dismayed by threats to pull out, and perplexed by the blame heaped upon the United Nations when U.S.-led operations such as the disastrous weekend helicopter attack there go wrong.

The bloody weekend roundup of warlord Mohammed Farah Aidid's lieutenants sent mixed signals. For more than 10 days, Secretary General Boutros Boutros-Ghali and the United Nations have been subjected to a barrage of American criticism for their costly and futile manhunt for Aidid while, according to the critics, ignoring the tasks of nation-building and reconciliation. Yet the U.S. forces, who could not have acted without Washington's approval, intensified the hunt Sunday night.

"With all the talk last week of seeking a political solution," a U.N. official said, "who would have expected a high-risk search operation?"

Although the operation was, as Clinton Administration officials were quick to insist, "under the authority of the United Nations," the U.S. Quick Reaction Force in Somalia and the U.S. Rangers have more independence of the U.N. chain of command than other troops in Somalia.

Neither Washington nor the United Nations has made the lines of control completely clear. But it is clear that the U.S. troops cannot be used without the Pentagon's consent. According to Pentagon sources, the American attack troops, still under the operational control of the U.S. Central Command in Tampa, Fla., report directly to Maj. Gen. Thomas M. Montgomery, the American who serves as the deputy U.N. military commander in Somalia. He has tactical command and can thus order the Americans into action quickly.

A senior U.N. peacekeeping official, while insisting that these U.S. troops are committed to action only "within the overall aim of the mandate of the U.N.," would not say who had ordered their Sunday deployment. But he did tell a news briefing that Washington is usually informed before the quick response force rushes into combat.

On the other hand, he refused to say whether anyone had informed the U.N. peacekeeping office in New York. He said that it is often not feasible for the U.S. troops to consult New York before launching a surprise raid to capture suspects. "As an old soldier," the official said, "I wouldn't want to hold them back and consult with 25 people. By that time, they (the suspects) would be in Ethiopia."