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President Obama came to office after campaigning against the secrecy of his predecessor's aggressive counterterrorism strategies, but the current administration now faces calls for greater accountability after U.S. airstrikes killed as many as three American citizens, including the radical cleric Anwar al-Awlaki.

The New Mexico-born Al-Awlaki was a key figure in the Al Qaeda branch in Yemen, and the airstrike that killed him and North Carolina native Samir Khan was generally hailed on Capitol Hill as a foreign policy victory.

Yet it also sets an unexpected precedent for a president who had consistently sought to distance himself from President Bush's policies. To complicate the matter, a second strike reportedly killed the cleric’s U.S.-born 16-year-old son, Abdulrahman al-Awlaki.

“I think the administration certainly put this issue in play during the campaign,” former Deputy Assistant Attorney General Thomas Dupree Jr. who served under President Bush, told Fox News.

“They were very critical, openly critical about the Bush administration -- alleged secrecy and non transparency -- that sort of thing. And so I think they set the bar fairly high as far as transparency in legal reasoning and legal authority goes,” he said.

Through the Freedom of Information Act, the ACLU wants all documents, legal opinions and evidence that justified the two separate U.S. strikes in Yemen.

The CIA-led operation Sept. 30 killed cleric al-Awlaki -- the first American on the CIA's kill or capture list -- and Khan, who was traveling with him. At the time, U.S. officials emphasized that Khan was not on the CIA kill list nor was he the target of the CIA-led operation.

A second strike reportedly killed the cleric’s son, who was born in Denver in 1995 after his father graduated from Colorado State University. On Tuesday, a State Department spokeswoman said the teenager’s death remained an open question.

“We’re not actually in a position to confirm it,” Victoria Nuland, a spokeswoman told reporters. “We have not been contacted by the family with regard to it.”

A Yemeni government source told Fox News that they could not confirm the teenager’s death either because no one in Yemeni government had seen the body – at one point suggesting that it may be in the al-Awlaki family’s interest to publicly state the boy is dead.

While initial reports after the mid-October strike suggested the son was a militant with Al Qaeda in his 20s, exclusive video, shot by Fox News and seen here as part of Fox News' ongoing investigation of the cleric al-Awlaki and his new generation of American recruits, suggests the son was well under the age of 18.

Sources who spoke to Fox News on the condition of anonymity, given the sensitive nature of the strike, said the teenager was not the intended target but he was traveling with a senior member of Al Qaeda– Ibrahim al-Banna – considered a top leader for the Yemeni network. Al-Banna was killed.

In its FOIA request, the ACLU writes: "The public has a vital interest in knowing the legal basis on which U.S. citizens maybe designated for extrajudicial killing and then targeted with legal force." The letter also raised questions about the quality of the evidence against al-Awlaki who U.S. officials have consistently described since the Spring of 2010 as an operational planner for Al Qaeda in Yemen. The group was behind the last two major attempted plots against the U.S. using planes.

In a press release the ACLU said the strikes raise “serious and troubling questions” adding that former government officials, from both sides of the aisle, have called for the release of legal memos that laid the basis for the strike.

“The government is hiding behind a veil of secrecy and is refusing to publicly release information about its justifications for killing U.S. citizens far from any active battlefield. We know from reports in the press that the Department of Justice Office of Legal Counsel (OLC) produced a memorandum providing legal justifications for killing al-Awlaki and that he was placed on a so-called "kill list" by a secret group of government officials. The government refuses to release the OLC memo or any other information about the legal and factual bases for killing Anwar and Abdulrahman al-Awlaki and Samir Khan, however.”

While on Oct. 5, the chair of the senate intelligence committee, Dianne Feinstein, said she believed Anwar al-Awlaki presented “a direct, imminent threat to the United States and that he was a lawful target under the laws of war,” the senior Democrat urged the Obama administration to “make public its legal analysis on its counterterrorism authorities, whether in the form of a legal opinion or a white paper…for both transparency and to maintain public support of secret operations.”

On Oct. 12, in his most recent public statement on the matter, White House spokesman Jay Carney would not confirm the memo’s existence. “I'm not going to discuss matters of that nature. I can simply say as a general matter of fact, that Mr. Awlaki was an operational leader of Al Qaeda in the Arabian Peninsula. He was directly involved in plots to perform -- that would have resulted in terrorist acts against the United States. And it is -- I think it's important to remember that when we assess this overall question.”

Asked if other Americans were targets on the kill list, Carney added “Again, I'm not going to -- as others who were here when this happened, I'm just not going to engage in a conversation about that.”

Dupree was also struck by the contrast between criticism of the Bush administration for waterboarding Al Qaeda detainees and the response to the reported deaths of three Americans under the Obama administration. Dupree warned that failing to provide some public explanation for the strikes may prompt the courts to intervene – in what has traditionally been – an executive branch authority.

“I think there are some people who would say wait a minute, it's important for us to set forth our legal reasoning, precisely to avoid a scenario where the federal courts step in and say we are going to sort this out by setting forth legal steps, legal procedures, that the president needs to follow.”

Fox News chief intelligence correspondent Catherine Herridge's bestselling book "The Next Wave: On the Hunt for Al Qaeda's American Recruits" is published by Crown. It draws on her reporting for Fox News into al-Awlaki and his new generation of recruits – Al Qaeda 2.0. It is the first book to fully investigate al-Awlaki’s American life, his connections to the hijackers, and the growing threat from Al Qaeda in Yemen and Somalia.