“We have things in our toolbox in addition to hammers. … One should not underestimate the possibility of the regime, itself, cracking,” Mr. Gates told NBC’s “Meet the Press.”
“Now, the no-fly zone and even the humanitarian side will have to be sustained for some period of time,” Mr. Gates said.
President Obama will address the nation on his administration’s priorities in Libya on Monday.
On Tuesday, a conference will be convened in London to discuss the situation in the North African nation and steps to avert a humanitarian disaster.
NATO states, the United Nations, the Arab League and the African Union have been invited to the meeting. A contact group of nations, made up of a broad representation of participants, will be set up to take the work forward.
The international community has barely engaged with the African Union on isolating the Gadhafi regime, and participants at the London conference are expected to explore this option.
Mahmoud Jibril, who was appointed by the rebels as prime minister of a provisional government last week, has not been officially invited to the conference but will be on its sidelines in the British capital.
Arab League participation is a key factor in the success of the conference.
The Arab League was the first to support a no-fly zone over Libya, but member states have been slow to step forward with assistance in this effort.
Only Qatar and the United Arab Emirates have contributed to the coalition’s effort. The UAE initially withheld support because it was upset over U.S. criticism of the crackdown in Bahrain. That annoyance has since dissipated, and Western officials insist no quid pro quo was involved.
Now that the UAE has come on board, other Arab nations may follow.
“Converting Arab political commitments into action is always harder than we would like,” the Western diplomat said.
But, he added, the fact that the Arab League made the historic decision to support a no-fly zone is an indicator of two things: “a recognition that the Arab spring has changed the rules of the game for a lot of them, and a strong belief among Arab leaders that Gadhafi is a liability for the Arab world and they will be better off without him.”
Ali S. Aujali, the former Libyan ambassador in Washington who has publicly disowned the Gadhafi regime, told The Washington Times he was pleasantly surprised by the Arab League’s position in the crisis.
“There is a wave of change, not only among the regimes and among the people, but also in the Arab institutions and the Arab organizations,” Mr. Aujali said.
Meanwhile, Mr. Jibril’s presence in London will give the international community the opportunity to meet with him and get a better sense of the rebels. Mrs. Clinton met Mr. Jibril in Paris earlier this month, and U.S. officials said she came away impressed.
France is the only country to give diplomatic recognition to the rebel government. Other Western nations want them to first build up their political credibility and capacity.
“What they tell us in private is that they do aspire to democratic values, but I think they will be the first to admit that they are not very well organized yet,” the Western diplomat said.
“The future of Libya is for the Libyans to work out, but it would be much easier for us to give them support if they are espousing values that we espouse,” he added.