Tripoli, Libya (CNN) -- More than seven months after the U.N. Security Council authorized NATO forces to protect demonstrators in Libya, the aerial bombing campaign operation that helped depose longtime leader Moammar Gadhafi ended here Monday at midnight.
"I think what has happened in Libya sends a very clear signal to autocratic regimes all over the world," NATO Secretary-General Anders Fogh Rasmussen told reporters earlier in the day after arriving in Tripoli from Brussels, Belgium.
"We have been mandated by the United Nations Security Council to protect civilians and that mission has been a great success," he told CNN during the flight. "We have prevented a massacre. We have saved countless lives. We have fully implemented the United Nations mandate. That was our mission and we have done what we promised to do."
But the Pentagon said Monday that the United States will continue monitoring Libya from the skies even after the end of formal NATO military operations.
"There will be some kind of overwatch role for a little while after the actual end," Pentagon spokesman, Capt. John Kirby said. "We are still working with our NATO allies on that." U.S. manned and unmanned aircraft played a key reconnaissance role in the Libya operation even after U.S. forces stopped taking the lead combat role.
And National Transitional Council spokesman Ahmed Bani told CNN that he was expecting the mission would be suspended rather than canceled. "To cancel it, in these circumstances, I don't think was the right decision, especially at this time," he said, citing the continued presence of pro-Gadhafi elements.
NATO's move comes after the United Nations Security Council last week rescinded its March mandate for military intervention to protect civilians targeted during anti-regime protests.
Susan Rice, the U.S. ambassador to the United Nations, said NATO's mission puts Libya on a path to freedom.
But she tempered her remarks with a word of caution.
"We're very concerned that, as we move forward, that the authorities make maximum effort to swiftly form an inclusive government that incorporates all aspects of Libyan society, and in which the rights of all Libyan people are fully and thoroughly respected, regardless of their gender, their religion, their region of origin," Rice said after the Security Council vote last Thursday.
"But for the United States, and, I think, for the United Nations Security Council, this closes what I think history will judge to be a proud chapter in the Security Council's history."
As of Monday, Operation Unified Protector had flown 7,943 total sorties, 1,851 strike sorties and 398 total strikes in which ordnance was dropped.
Momentum to end the campaign began building after Gadhafi was killed following his capture near his hometown of Sirte on October 20.
Many British military personnel who had been stationed at an Italian airfield for the campaign already are returning home.
Meanwhile, Gadhafi's relatives said they plan to file a war crimes complaint.
"All of the events that have taken place since February 2011 and the murder of Gadhafi, all of this means we are totally in our right to call upon the International Criminal Court," Marcel Ceccaldi, a lawyer representing the family, said last week.
Questions have been raised about how Gadhafi was killed.
Amateur videos showed him alive when captured by the opposition. He died from a shot in the head, officials said, but the circumstances surrounding the shot remain unclear.
NATO's Libya campaign began in March, after the Security Council adopted Resolution 1973, which imposed a no-fly zone in the country's airspace and authorized member states to take measures to protect civilians.
CNN's Jomana Karadsheh contributed to this story.