United Nations ? The United States called Monday for the quick deployment of an expanded U.N. force in southern Lebanon and said a new U.N. resolution may be needed later to focus on disarming Hezbollah militants and enforcing an arms embargo.

Italy offered to replace France as head of the force after Paris disappointed top U.N. and U.S. officials by making only a small pledge of 400 troops. By contrast, Italy has indicated it would be prepared to send 3,000 soldiers. If Rome follows through, other European countries might be more willing to commit troops, as the U.S. has been urging.

Noting the fragility of the Israeli-Hezbollah cease-fire, U.S. Ambassador John Bolton made clear that the top priority for the United States is to get an additional 3,500 soldiers on the ground by next Monday and then quickly increase the force to 15,000 troops, joining an equal number of Lebanese troops.

But he said the issue of disarming Hezbollah, key to establishing lasting peace between Lebanon and Israel, will likely have to be addressed “in due course” in a new resolution.

Hezbollah is already required to disarm under a September 2004 U.N. resolution, and council diplomats are certain to look carefully at exactly what a new resolution would do. If it authorizes the U.N. force to disarm the guerrillas, there would likely be strong opposition from those who believe that disarmament should be carried out only as a result of an agreement between Hezbollah and the Lebanese government.

But in any event, getting boots on the ground is key, said Bolton’s spokesman, Richard Grenell.

“It’s premature to talk about the timing of a second resolution at this point,” he said. “Our priority right now is to get a robust international force on the ground.”

While several Muslim nations have pledged troops to the new force, there have been no major pledges from European countries. The U.S. wants broad European participation to ensure that the U.N. contingent is balanced and broadly acceptable to both the Israelis and Lebanese.