Nato is taking over the job of enforcing the no-fly zone over Libya, after leaders of the 28-nation alliance reached a compromise deal at the end of six days' wrangling.
But Nato will not assume responsibility for the time being for other military operations in the north African state, leaving the US, Britain and France to continue attacks on dictator Muammar Gaddafi's forces on the ground.
Talks over the prospect of Nato taking on a broader role will continue in Brussels, but US Secretary of State Hillary Clinton made clear that this would have to involve the alliance accepting the "political guidance" of all nations involved in the coalition, including Arab states.
It is thought that diplomats envisage an arrangement under which decisions on strategic and political goals would be taken by a "steering group" representing all coalition nations, while day-to-day operations are left to Nato.
President Barack Obama has made clear from the start of the Libyan crisis that he wants the US to step back from its leading role after the opening phase of the military campaign, and Thursday night's agreement allows this process to begin.
Speaking in Washington, Mrs Clinton said that, after five days of bombardment by British, American and French forces, "a massacre in Benghazi has been prevented, Gaddafi's air force and air defences have been rendered largely ineffective and the coalition is in control of the skies of Libya".
The United Arab Emirates has announced that it was becoming the second Arab state, after Qatar, to send warplanes to enforce the no-fly zone mandated by last week's UN Security Council resolution 1973.
Announcing the Nato agreement in Brussels, the alliance's secretary-general, Anders Fogh Rasmussen said: "At this moment there will still be a coalition operation and a Nato operation. But we are considering whether Nato should take on the broader responsibility in accordance with the UN Security Council resolution, but that decision has not been reached yet."
Mrs Clinton - who will next Tuesday travel to London for an international summit on Libya hosted by Foreign Secretary William Hague - said: "From the start, President Obama has stressed that the role of the US military would be limited in time and scope.
"Nato is well-suited to co-ordinating this international effort and ensuring that all participating nations are working effectively together toward our shared goals. This coalition includes countries beyond Nato, including Arab partners, and we expect all of them to provide important political guidance going forward."