7 Craziest Intelligence Leaks in US History

whistle-blowers, NSA, N.S.A., Edward Snowden — Edward Snowden, 29, spoke with the Guardian's Glenn Greenwald about his motives for leaking National Security Agency surveillance information in one of U.S history's biggest intelligence leaks.

(Image credit: Screenshot, The Guardian)

The news that the U.S. government has been recording data from phone calls and Internet activity, broken by former CIA employee Edward Snowden, is just the latest in a long line of legendary leaks. Here are some of the most notorious leaks in U.S. history.

The Pentagon Papers

What may be the most famous leak in U.S. history occurred in June 1971, when The New York Times published sections of a top-secret Department of Defense report on the country's involvement in Vietnam from 1945-1967. Dubbed the "Pentagon Papers," the report detailed how the Johnson administration and others repeatedly misled Congress and the public about the causes and progress of the Vietnam War, according to the History Channel. [7 Great Dramas in Congressional History]

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The report was leaked by antiwar activist Daniel Ellsberg, a former Defense Department analyst working for the RAND Corp., who stole it from the Pentagon and sent copies to the Times. The Pentagon Papers' publication fueled the antiwar movement and sparked a debate over the freedom of the press to divulge "classified" information and the public's right to know about government affairs. President Richard Nixon tried but failed to get the Supreme Court to prevent further publication of the papers.

One of the best-known leaks, of course, is the Watergate scandal of Richard Nixon's presidency. On June 17, 1972, five men were arrested for breaking into the headquarters of the Democratic National Committee at the Watergate hotel complex in Washington, D.C., and installing illegal wiretaps. The men were linked to a fundraising group for Nixon's 1972 re-election campaign, but the Nixon administration denied any involvement.

Later in 1972, Washington Post reporters Carl Bernstein and Bob Woodward exposed the administration's role in the scandal and cover-up. Their key source was an informant nicknamed "Deep Throat," who was later revealed to be former FBI agent W. Mark Felt. A series of Senate hearings nailed the lid on Nixon's coffin, and he resigned from the presidency in 1974 — the first president to do so. [The 10 Weirdest Presidential Inaugurations in US History]

The so-called "Iraq War Logs" were just one of many leaks made by the non-profit organization WikiLeaks, founded by Australian journalist and activist Julian Paul Assange. The organization publishes secret or classified information or news from anonymous sources. In October 2010, WikiLeaks published Army field reports from 2004 to 2009 that listed the number of civilian deaths as 66,081 out of 109,000 total recorded deaths. The leaked logs confirmed some partially reported events. For instance, some American troops had been classifying civilian deaths as enemy deaths. The Iraq War Logs represent the largest leak in U.S. history.

In 2003, a case of leaked identity ended the career of a CIA agent. On July 6, 2003, The New York Times published an Op-Ed by former U.S. diplomat Joseph Wilson, which questioned the reasons given by President George W. Bush's administration for invading Iraq earlier in 2003. Wilson, who had been a CIA envoy to Niger in 2002, said Bush's claim that Iraq had attempted to buy enriched uranium yellowcake — a step toward enriched uranium but not weapons-grade yet — from Niger was unsubstantiated. In response, Washington Post columnist Robert Novak wrote a column on July 14, 2003 criticizing Wilson and referring to Wilson's wife, Valerie Plame, as an "agency operative" — blowing her cover. Wilson accused the White House of leaking Plame's identity as retribution for his Op-Ed, prompting an investigation. Prosecutor Patrick Fitzgerald interviewed Bush, Vice President Dick Cheney and other administration officials and journalists. New York Times reporter Judith Miller, who conducted interviews in the leak but had never written an article about it, refused to testify and was held in contemp. She served time at a federal detention center, but was released after three months when Lewis "Scooter" Libby, Cheney's chief of staff, signed a waiver granting Miller permission to speak.

Named in the Watergate tradition, "Climategate" refers to a controversy in the fall of 2009 in which hackers leaked thousands of emails and documents from the Climatic Research Unit (CRU) at the University of East Anglia, United Kingdom. The documents appeared to show scientists suppressing the publication of research undermining the existence of global warming. Even though an investigation later revealed no foul play was afoot, the leak added fuel to the global warming debate. Climate change critics claimed the leaked emails showed that global warming was a conspiracy among scientists, while the CRU said the emails were taken out of context.

Not all leaks are about exposing the truth — some are about deception. Such was the case with Operation Mincemeat, a leak planned and executed by the Allies during World War II. The plan, part of the larger Operation Barclay, was intended to make the Germans think the Allies were planning to invade Greece and Sardinia instead of Sicily. The Allies put fake "top secret" invasion plans on a dead body that was left to wash up on a beach in Spain. The plan worked: The Germans found the body and copied the fake plans. The trickery made the Germans suspicious, so they ignored other real intelligence leaks, thinking they were ruses.

On June 6, 2013, The Guardian broke the news that the U.S. National Security Agency (NSA) has been collecting the phone records of millions of customers of Verizon, the U.S. telecom provider, as authorized by a top-secret court order issued in April. Technical contractor and former CIA employee Edward Snowden leaked classified details of a top-secret NSA electronic surveillance program, codenamed PRISM, to The Washington Post and The Guardian.

Via this program, the NSA can obtain information such as email, voice and video chat, other videos, photos, and social networking details, according to The Guardian. The NSA and FBI are obtaining data from the central servers of nine major Internet companies, including Google, Facebook and Apple, The Washington Post reported. The leak has launched criticism of President Barack Obama's administration over breach-of-privacy concerns. The president has defended the surveillance program, claiming it has helped prevent terrorist attacks. The controversy continues, as more details of the surveillance programs are unveiled.

Tanya was a staff writer for Live Science from 2013 to 2015, covering a wide array of topics, ranging from neuroscience to robotics to strange/cute animals. She received a graduate certificate in science communication from the University of California, Santa Cruz, and a bachelor of science in biomedical engineering from Brown University. She has previously written for Science News, Wired, The Santa Cruz Sentinel, the radio show Big Picture Science and other places. Tanya has lived on a tropical island, witnessed volcanic eruptions and flown in zero gravity (without losing her lunch!). To find out what her latest project is, you can visit her website.