WASHINGTON  The United States began moving warships toward Libya and froze $30 billion in the country’s assets on Monday as the administration declared all options on the table in its diplomatic, economic and military campaign to drive Col. Muammar el-Qaddafi from power.

Secretary of State Hillary Rodham Clinton said the administration was conferring with allies about imposing a no-fly zone over Libya. Such a move would likely be carried out only under a mandate from the United Nations or NATO, but Mrs. Clinton’s blunt confirmation that it was under consideration was clearly intended to ratchet up the pressure on Colonel Qaddafi and his dwindling band of loyalists.

“Qaddafi has lost the legitimacy to govern, and it is time for him to go without further violence or delay,” Mrs. Clinton told reporters after a special meeting of the United Nations Human Rights Council. “No option is off the table,” she said, adding “that of course includes a no-fly zone.”

But officials in Washington and elsewhere said that direct military action remained unlikely, and that the moves were designed as much as anything as a warning to Colonel Qaddafi and a show of support to the protesters seeking to overthrow his government.