The US Army has arrested Specialist Bradley Manning, a soldier deployed in Iraq with the 10th Mountain Division, on charges that he allegedly released classified information. The military is looking at a possible connection between Spc. Manning and WikiLeaks, an online whistleblower organization which in April published a graphic video of an Apache gunship mistakenly shooting civilians, according to Pentagon spokesman Bryan Whitman.

“The Department of Defense takes the management of classified information very seriously because it affects our national security, the lives of our soldiers, and our operations abroad,” said a statement released by the Pentagon.

The Manning case marks the third time during the Obama administration that authorities have arrested a suspected leaker.

This “seems to reflect an increasingly aggressive response to unauthorized disclosures of classified information,” writes Steven Aftergood, director of the Project on Government Secrecy for the Federation of American Scientists, on his Secrecy News blog.

Manning is in pretrial custody in Kuwait, according to the Army. Wired.com reported that he was caught after he boasted to a former computer hacker of leaking hundreds of thousands of classified documents and the combat video footage, including the gun camera videos of the deadly 2007 Baghdad incident subsequently posted on WikiLeaks.

The former hacker, Adrian Lamo, turned Manning in to the FBI, according to Wired, which broke the news of the arrest.

The Army video published by WikiLeaks is 38 minutes of an aerial mission over Baghdad in which a gunship crew follows and then fires upon a group of men it believes to be militants. In fact, at least two members of the group were civilians – Iraqi natives employed by Reuters as journalists.

The Reuters employees were killed in the attack.

Manning’s arrest may be the result of a Justice Department crackdown on leaks to the press.

In May, FBI linguist Shamai Leibowitz was sentenced to 20 months in prison after pleading guilty to passing classified information to a blogger.

In April, former National Security Agency senior executive Thomas Drake was indicted on charges related to the possession of classified information and obstruction of justice. The indictment alleges that in 2006 and 2007 Drake passed along highly classified data to a newspaper reporter, who wrote a series of articles about the NSA based on the information.

The Obama White House would be far from the first administration bedeviled by leaks.

At a May 12 hearing of a Senate Judiciary Committee subcommittee on terrorism, former CIA general counsel Jeffrey Smith noted that every administration in which he had served had suffered from leaks he considered to be harmful.

“And every administration has struggled to solve the problem, but none has had much success,” said Mr. Smith.

Absent a guilty plea, as occurred in the case of Mr. Leibowitz, leak prosecutions are notoriously difficult.

Finding the leaker in the first place is hard, said Kenneth Wainstein, a former Assistant Attorney General for National Security, at the May 12 Senate hearing. Producing incriminating evidence is also difficult, since in most cases prosecutors are reluctant to subpoena the receivers of leaks – members of the press.

Agencies from which the information was leaked are often not eager to prosecute, on the theory that open court proceedings might simply reveal more classified information. Plus, leak cases are often marked by zealous and novel legal defenses.

“For all these reasons, leak cases, especially leak cases to the media, are exceptionally challenging,” said Mr. Wainstein.

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