'Rebels' were involved in overthrow of the regimes of Iranian president Mohammad Mossadeq removed in 1953, and Jacobo Arbenz in 1954, but in both cases the CIA was behind the 'rebels'. In both cases, CIA operations were clear cases of counterinsurgency operations presented to the world as genuine uprisings. If one considers CIA operations as intended to install reactionary regimes, which is what took place in Iran where the Shah was installed and in Guatemala where a military dictatorship was put in place, then CIA operations cannot be classified as anything but reactionary!
With regard to Libya in 2011, CIA operations were not intended to bring to power revolutionary or reformist regime after Gaddafi, but a pro-EU and pro-US one that caters to business on better terms than Gaddafi who started out as a revolutionary, pro-non-aligned and remains a favorite of reformist-friendly regimes, including a number of them in Latin America. That the CIA, MI-6 and French intelligence were involved in the anti-Gaddafi rebel movement indicates that the rebels will lose their legitimacy at home and abroad, especially when they become almost entirely dependent on US, UK and France for toppling the government, instead of relying on grass roots support entirely without foreign power intervention.
Some right wingers have suggested that the CIA, MI-6 and French intelligence were on the side of the people wanting a democratic regime. This is designed to prove that the US, UK, and France are carrying out policies on behalf of the Libyan people, interested in their current and future welfare, when in reality these countries are only interested in economic, strategic and diplomatic benefits accruing to them from a pro-West regime in Libya. If the West is interested in advancing the welfare of Libyan people, they could begin by helping their own middle class and workers.
The idea that the CIA has ever carried out pro-insurgency operations is not only absurd as theory, but impossible as practice given that the agency serves a status quo power whose goal is to prevent not only revolutions, but reform that may dilute the political economy of capitalism. However, if one is stuck in the Oliver North-Ronald Reagan mentality, then the CONTRAS were rebels and the CIA was helping to carry out a pro-insurgency campaign against the duly-elected regimes in Managua. One could argued that the CIA logo may change to show the effigy of CHE, now that the agency is on the side of rebels!
Official statements and investigative reporting from around the world, oftentimes from a government that will reveal a piece of information because it opposes the policy of another government. Can I prove 100% that CIA, MI-6 and French intelligence was operating in Libya? Not unless I have archival - first hand official government material. For now, we rely only on secondary sources that could be wrong because the authors speculate on circumstantial evidence.
For example, if it has been confirmed through various sources that in rebel areas in Libya - Tobuk, Benghazi and Darnah - there have been historically Islamic militants, including al-Qaeda, that had an understanding with Gaddafi not to hit any domestic targets, are we to conclude that these 'rebels' are progressive in any sense of the word; are we to speculate what in the world was the US doing collaborating with such groups that would otherwise be called 'terrorist'; are we to conclude that Gaddafi was a much bigger threat to remove from power for US, UK, and France than the smaller and divided 'Islamist rebels'?