WASHINGTON (AP) - Newly declassified documents offer more details of how the CIA executed the overthrow of Iran's democratically elected prime minister 60 years ago, describing the political frustrations that led the U.S. to take covert action against a Soviet ally - and echoing the current frustrations with Iran over its nuclear ambitions. It's long been known that the United States and Britain played key roles in the overthrow of Iranian Prime Minister Mohammed Mossadegh - a move that still poisons Tehran's attitude toward both nations. The CIA acknowledged its role previously, even including it in the timeline on its public website last year: "19 August 1953 CIA-assisted coup overthrows Iranian Premier Mohammed Mossadegh." Mossadegh was replaced by the oppressive regime of Shah Reza Pahlavi, who was overthrown in 1979 by followers of Ayatollah Ruhollah Khomeini in the Iranian revolution of 1979. But for historians, the heavily redacted documents posted this week on George Washington University's National Security Archive amount to "the CIA's first formal acknowledgement that the agency helped to plan and execute the coup," the archive said on its site. The documents also offer an explanation for the covert action that's eerily similar to arguments for curbing Iran's nuclear ambitions today. The CIA argued then that Iran was threatening Western security by not cooperating with the West - at the time, by refusing to bargain with the British-run Anglo-Iranian Oil Co. - thereby threatening the supply of cheap oil to Britain and risking a British invasion that could in turn trigger a counter Soviet invasion of Iranian oilfields. The documents outline how the Iranian political earthquake was to be undertaken. One paper titled "Campaign to Install Pro-Western Government in Iran Authority" lists the objectives as "through legal, or quasi-legal, methods, to effect the fall of the Mossadegh government" including "exposing his collaboration with the Communists" and "to replace it with a pro-Western government under the Shah's leadership." In a document titled "The Battle for Iran," the CIA reveals the coup plan was called "Operation TPAJAX." The unnamed author of the history writes that previously published accounts miss the point that "the military coup that overthrew Mossadegh ... was carried out under CIA direction as an act of U.S. foreign policy, conceived and approved at the highest levels of government." The author adds that the coup plan was "an official admission (redacted) that normal, rational methods of international communication and commerce had failed. TPAJAX was entered as a last resort. The once-secret papers also outline the British government's unease when U.S. diplomats revealed in the late 1970s that the U.S. and British roles in the overthrow might be made public with the eventual release of such documents under the new U.S. Freedom of Information Act - the same act the Washington-based National Security Archive used to get the latest release. "I requested these particular materials in 2000 and it took 11 years to get them," the archive's Malcolm Byrne said in an email to The Associated Press on Tuesday. Iranian leaders have been asking for an official apology ever since the coup. The U.S. and Iran remain at odds over Iran's plans to build up its nuclear power system, and allegedly, nuclear weapons capability. President Bill Clinton came close to apologizing in oblique comments in 1999, and President Barack Obama acknowledged the U.S. actions in his Cairo speech in 2009. "In the middle of the Cold War, the United States played a role in the overthrow of a democratically elected Iranian government," Obama said to the Egyptian audience, citing that as a reason for tension between the two countries. No U.S. leader has explicitly apologized, and the White House offered no immediate comment Tuesday on the new disclosures.