The arrest of a 21-year-old airman in the Massachusetts Air National Guard after he was accused of posting hundreds of classified documents online is the latest incident of leaked material in the U.S. since World War II.

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The FBI took airman first class Jack Teixeira, 21, of Dighton, into custody without incident on Thursday at his home. Officials accused him of unauthorized retention and transmission of national defense information and unauthorized removal and retention of classified documents or material.

On Friday, Teixeira was charged with two counts under the Espionage Act, according to The New York Times. He did not enter a plea.

He joined the Air National Guard in September 2019, was promoted to Airman 1st Class in July, and held the highest level security clearance granted by the federal government for top secret information, according to an internal Department of Defense email.

Here are three of the biggest intelligence leaks since the 1960s.

NSA leaks

Edward Snowden leaked a cache of intelligence documents to The Washington Post and The Guardian in 2013. The information showed that the U.S. government was illegally collecting the telephone data of citizens, the BBC reported.

Snowden was a tech specialist who contracted for the National Security Agency and worked for Booz Allen Hamilton, a consulting firm, the Post reported.

The documents revealed sensitive information about the NSA, according to the BBC.

The surveillance program came after the terrorist attacks on Sept. 11, 2001, The Hill reported.

Snowden was charged with stealing government property and violating the Espionage Act, according to NPR. He left the U.S. in 2013 and intended to go to Ecuador. However, he received temporary asylum in Russia and became a citizen of that country in 2022, according to the news organization.

He has become an advocate for protecting journalists against surveillance, according to the BBC.

Snowden tweeted in November 2020 after staying in Russia that he and his wife would “remain Americans, raising our son with all the values of the America we love -- including the freedom to speak his mind.

“And I look forward to the day I can return to the States, so the whole family can be reunited.”

WikiLeaks

WikiLeaks, a media organization founded by Julian Assange, published leaked classified military documents in 2010, according to The Hill. The documents detailed the actions of U.S. and coalition forces during the Iraq war from 2004 to 2009.

The documents from U.S. military and intelligence services were leaked by Chelsea Manning, a U.S. Army soldier and intelligence analyst, NPR reported.

Assange worked with reporters at publications including The New York Times, The Guardian and the German magazine Der Spiegel to publish the leaks. Eric H. Holder Jr., then the attorney general, announced a criminal investigation of WikiLeaks.

In May 2019, an 18-count federal indictment alleged that Assange worked with Manning to obtain and disseminate secret documents. the Post reported.

Media lawyer Floyd Abrams told the newspaper that Assange may be a “singularly unattractive defendant in a lot of ways” but said that the indictment “does raise deeply threatening First Amendment issues for journalists who cover national defense, intelligence activities, and alike.”

Justice Department officials decided they could not prosecute Assange for sharing information because it risked setting a precedent that could erode press freedoms for news organizations, the Times reported.

In 2019, Snowden told NPR that he shared the classified information to protest the excessive collection of data on Americans by the government and others.

“Where this data that your (smart) refrigerator was collecting, that your phone was collecting, that the government was collecting -- where all of this data was going was intentionally hidden from us,” Assange told NPR. “We are no longer partner to our technology, in large part, just as we are increasingly, unfortunately, no longer partner to our government, so much as subject to them. And this is a dangerous trend.”

Assange has been confined at the Belmarsh high-security prison in the United Kingdom since 2019, The Associated Press reported. In June 2022 the British government ordered the extradition of Assange to the U.S., the news organization reported. Assange appealed the ruling and remains at the British prison, according to The Guardian.

Pentagon Papers

Daniel Ellsberg was an analyst for a top-secret Defense study into the U.S. involvement in the Vietnam War, He eventually leaked portions of the report to The New York Times, which published excerpts in 1971. The revelations in the Pentagon Papers infuriated the country, validating many of the criticisms leveled at the U.S. government for getting involved in Southeast Asia.

Ellsberg secretly photographed the report in October 1969, according to the Post. Its contents detailed U.S. policy decisions between 1945 and 1967, The Hill reported.

Officially titled “Report of the Office of the Secretary of Defense Vietnam Task Force,” the papers filled 47 volumes, the Times reported.

Convinced that Ellsberg posed a threat to Richard Nixon’s re-election campaign in 1972, the White House approved an illegal break-in at the Beverly Hills, California, office of Ellsberg’s psychiatrist, according to the newspaper.

An ensuing court battle to stop the publication of the papers, New York Times Company v. United States, was decided in the newspaper’s favor by a 6-3 decision. The three-paragraph decision stated that the government had not overcome a “heavy presumption” against prior restraints, the Times reported.

The case remains one of the most important cases for press freedom in U.S. history, according to The Hill.

Ellsberg was initially charged with espionage, but a judge dismissed the charges in 1973, the BBC reported.