The extension of Operation Unified Protector authorizes NATO to continue operations, including airstrikes, in Libya through September, Rasmussen said at NATO headquarters in Brussels, Belgium, after meeting with NATO defense ministers, the U.S. Department of Defense reported.
"If you look at the situation we have in Libya now and compare it with the situation when Operation Unified Protector began," he said, "it is clear how much NATO and its partners have achieved. … We have preserved innocent lives by keeping the air and sea open for humanitarian aid, even while we closed it to weapons and mercenaries," Rasmussen said.
Earlier Wednesday, Rasmussen said Moammar Gadhafi's departure from power could come at any time as the NATO leader offered an implicit endorsement to the rebel-led government in Libya.
Rasmussen said the Libyan leader "is history" as the military alliance conducted the most intense bombardment of Tripoli since operations began in March, The Washington Post reported Wednesday.
The Libyan government has accused NATO of trying to assassinate Gadhafi, a charge NATO has repeatedly denied.
"Gadhafi's reign of terror is coming to an end and we must be prepared for when it is over," Rasmussen said after meeting with defense ministers from the countries involved in the Libya operation.
Rasmussen also offered an endorsement of the Transitional National Council, the rebel-led government in the eastern part of Libya.
"I feel confident that they are sincere in their desire to see a true democracy developed in Libya," Rasmussen said.
Rasmussen said he believes the United Nations should take a leading role in any post-Gadhafi Libya and that he had no intention of committing NATO ground troops to ensure security should Gadhafi step down.
U.S. Defense Secretary Robert Gates Wednesday criticized other NATO members for not doing their part in the 2-month-old air war.
Gates, in a closed-door meeting, singled out Germany and Poland for not contributing their assets and capabilities to assist in the operation, the Financial Times reported.
He also called on Spain, Turkey and the Netherlands to increase their participation either through ground-attack sorties, reconnaissance or in-air refueling operations.
"The burden of the strike mission is being borne by eight allies," a senior U.S. official told the Times. "Crews are getting tired, the stress on the airplanes is significant, and you're finding that already in key allies as they consider how they can continue and extend their operations … .
"The main point is if you're in the operation and you're not doing everything you can, you should," the official said. "And if you're not in the operation, it's high time that you do."