Story highlights FIRST ON CNN : New documents formed the basis of story on news site, Intercept

: New documents formed the basis of story on news site, Intercept The site is run by Glenn Greenwald, who published leaks by Edward Snowden

Article focuses on the growth of names on terror databases during the Obama administration

The federal government has concluded there's a new leaker exposing national security documents in the aftermath of surveillance disclosures by former NSA contractor Edward Snowden, U.S. officials tell CNN.

Proof of the newest leak comes from national security documents that formed the basis of a news story published Tuesday by the Intercept, the news site launched by Glenn Greenwald, who also published Snowden's leaks.

The Intercept article focuses on the growth in U.S. government databases of known or suspected terrorist names during the Obama administration.

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Photos: Sharing secrets: U.S. intelligence leaks Photos: Sharing secrets: U.S. intelligence leaks Sharing secrets: U.S. intelligence leaks – John Walker ran a father and son spy ring, passing classified material to the Soviet Union from 1967 to 1985. Walker was a Navy communication specialist with financial difficulties when he walked into the Soviet Embassy and sold a piece of cyphering equipment. Navy and Defense officials said that Walker enabled the Soviet Union to unscramble military communications and pinpoint the location of U.S. submarines at all times. As part of his plea deal, prosecutors promised leniency for Walker's son Michael Walker, a former Navy seaman. Click through the gallery to see other high-profile leak scandals the United States has seen over the years. Hide Caption 1 of 10 Photos: Sharing secrets: U.S. intelligence leaks Sharing secrets: U.S. intelligence leaks – Military analyst Daniel Ellsberg leaked the 7,000-page Pentagon Papers in 1971. The top-secret documents revealed that senior American leaders, including three presidents, knew the Vietnam War was an unwinnable, tragic quagmire. Further, they showed that the government had lied to Congress and the public about the progress of the war. Ellsberg surrendered to authorities and was charged as a spy. During his trial, the court learned that President Richard Nixon's administration had embarked on a campaign to discredit Ellsberg, illegally wiretapping him and breaking into his psychiatrist's office. All charges against him were dropped. Since then he has lived a relatively quiet life as a respected author and lecturer. Hide Caption 2 of 10 Photos: Sharing secrets: U.S. intelligence leaks Sharing secrets: U.S. intelligence leaks – Jonathan Pollard is a divisive figure in U.S.-Israeli relations. The former U.S. Navy intelligence analyst was caught spying for Israel in 1985 and was sentenced in 1987 to life imprisonment. Previously, the United States and Israel discussed his possible release as part of efforts to save fragile Middle East peace negotiations, according to sources familiar with the talks. On July 28, 2015, Pollard's lawyer announced that the convicted spy had been granted parole and would be released on November 21 -- exactly 30 years after his arrest. Hide Caption 3 of 10 Photos: Sharing secrets: U.S. intelligence leaks Sharing secrets: U.S. intelligence leaks – Wen Ho Lee was a scientist at the Los Alamos Laboratory in New Mexico who was charged with 59 counts of downloading classified information onto computer tapes and passing it to China. Lee eventually agreed to plead guilty to a count of mishandling classified information after prosecutors deemed their case to be too weak. He was released after nine months in solitary confinement. Lee later received a $1.6 million in separate settlements with the government and five news agencies after he sued them, accusing the government of leaking damaging information about him to the media. Hide Caption 4 of 10 Photos: Sharing secrets: U.S. intelligence leaks Sharing secrets: U.S. intelligence leaks – Members of the Bush administration were accused retaliating against Valerie Plame, pictured, by blowing her cover in 2003 as a U.S. intelligence operative, after her husband, former Ambassador Joe Wilson, wrote a series of New York Times op-eds questioning the basis of certain facts the administration used to make the argument to go to war in Iraq. Hide Caption 5 of 10 Photos: Sharing secrets: U.S. intelligence leaks Sharing secrets: U.S. intelligence leaks – In 2007, Lewis "Scooter" Libby, Vice President Dick Cheney's former chief of staff, was convicted on charges related to the leak of the identity of CIA operative Valerie Plame. Libby was convicted of obstruction of justice and perjury in connection with the case. His 30-month sentence was commuted by President George W. Bush. Cheney told a special prosecutor in 2004 that he had no idea who leaked the information. Hide Caption 6 of 10 Photos: Sharing secrets: U.S. intelligence leaks Sharing secrets: U.S. intelligence leaks – Aldrich Ames, a 31-year CIA employee, pleaded guilty to espionage charges in 1994 and was sentenced to life in prison. Ames was a CIA case worker who specialized in Soviet intelligence services and had been passing classified information to the KGB since 1985. U.S. intelligence officials believe that information passed along by Ames led to the arrest and execution of Russian officials they had recruited to spy for them. Hide Caption 7 of 10 Photos: Sharing secrets: U.S. intelligence leaks Sharing secrets: U.S. intelligence leaks – Robert Hanssen pleaded guilty to espionage charges in 2001 in return for the government not seeking the death penalty. Hanssen began spying for the Soviet Union in 1979, three years after going to work for the FBI and prosecutors said he collected $1.4 million for the information he turned over to the Cold War enemy. In 1981, Hanssen's wife caught him with classified documents and convinced him to stop spying, but he started passing secrets to the Soviets again four years later. In 1991, he broke off relations with the KGB, but resumed his espionage career in 1999, this time with the Russian Intelligence Service. He was arrested after making a drop in a Virginia park in 2001. Hide Caption 8 of 10 Photos: Sharing secrets: U.S. intelligence leaks Sharing secrets: U.S. intelligence leaks – Army Pvt. Bradley Manning was convicted July 30 of stealing and disseminating 750,000 pages of classified documents and videos to WikiLeaks, and the counts against him included violations of the Espionage Act. He was found guilty of 20 of the 22 charges but acquitted of the most serious charge -- aiding the enemy. Manning was sentenced to 35 years in military prison in 2013. Hide Caption 9 of 10 Photos: Sharing secrets: U.S. intelligence leaks Sharing secrets: U.S. intelligence leaks – Former intelligence contractor Edward Snowden revealed himself as the leaker of details of U.S. government surveillance programs run by the U.S. National Security Agency to track cell phone calls and monitor the e-mail and Internet traffic of virtually all Americans. Snowden has been granted temporary asylum in Russia after initially fleeing to Hong Kong. He has been charged with three felony counts, including violations of the U.S. Espionage Act, over the leaks. Hide Caption 10 of 10

Photos: Notable leakers and whistle-blowers Photos: Notable leakers and whistle-blowers Former intelligence worker Edward Snowden revealed himself as the source of documents outlining a massive effort by the NSA to track cell phone calls and monitor the e-mail and Internet traffic of virtually all Americans. He says he just wanted the public to know what the government was doing. "Even if you're not doing anything wrong, you're being watched and recorded," he said. Snowden has been granted temporary asylum in Russia after initially fleeing to Hong Kong. He has been charged with three felony counts, including violations of the U.S. Espionage Act, over the leaks. Hide Caption 1 of 15 Photos: Notable leakers and whistle-blowers Military analyst Daniel Ellsberg leaked the 7,000-page Pentagon Papers in 1971. The top-secret documents revealed that senior American leaders, including three presidents, knew the Vietnam War was an unwinnable, tragic quagmire. Further, they showed that the government had lied to Congress and the public about the progress of the war. Ellsberg surrendered to authorities and was charged as a spy. During his trial, the court learned that President Richard Nixon's administration had embarked on a campaign to discredit Ellsberg, illegally wiretapping him and breaking into his psychiatrist's office. All charges against him were dropped. Since then he has lived a relatively quiet life as a respected author and lecturer. Hide Caption 2 of 15 Photos: Notable leakers and whistle-blowers Starting in 1932, the U.S. Public Health Service studied untreated syphilis in black men who thought they were getting free health care. The patients weren't told of their affliction or sufficiently treated. Peter Buxtun, who worked for the Public Health Service, relayed information about the Tuskegee syphilis experiment to a reporter in 1972, which halted the 40-year study. His testimony at congressional hearings led to an overhaul of the Health, Education and Welfare rules concerning work with human subjects. A class-action lawsuit was settled out-of-court for $10 million, with the U.S. government promising free medical care to survivors and their families. Here, participants talk with a study coordinator. Hide Caption 3 of 15 Photos: Notable leakers and whistle-blowers In 2005, retired deputy FBI director Mark Felt revealed himself to be the whistle-blower "Deep Throat" in the Watergate scandal. He anonymously assisted Washington Post reporters Carl Bernstein and Bob Woodward with many of their stories about the Nixon administration's cover-up after the June 1972 break-in at the Democratic National Committee headquarters. The stories sparked a congressional investigation that eventually led to President Nixon's resignation in 1974. The Post won a Pulitzer Prize for its coverage. Felt was convicted on unrelated conspiracy charges in 1980 and eventually pardoned by President Ronald Reagan before slipping into obscurity for the next quarter-century. He died in 2008 at age 95. Hide Caption 4 of 15 Photos: Notable leakers and whistle-blowers Mordechai Vanunu , who worked as a technician at Israel's nuclear research facility, leaked information to a British newspaper and led nuclear arms analysts to conclude that Israel possessed a stockpile of nuclear weapons. Israel has neither confirmed nor denied its weapons program. An Israeli court convicted Vanunu in 1986 after Israeli intelligence agents captured him in Italy. He was sentenced to 18 years in prison. Since his release in 2004, he has been arrested on a number of occasions for violating terms of his parole. Hide Caption 5 of 15 Photos: Notable leakers and whistle-blowers President Ronald Reagan addresses the media in 1987, months after the disclosure of the Iran-Contra affair . A secret operation carried out by an American military officer used proceeds from weapons sales to Iran to fund the anti-communist Contras in Nicaragua and attempted to secure the release of U.S. hostages held by Iran-backed Hezbollah in Lebanon. Mehdi Hashemi, an officer of Iran's Islamic Revolutionary Guards Corps, leaked evidence of the deal to a Lebanese newspaper in 1986. Reagan's closest aides maintain he did not fully know, and only reluctantly came to accept, the circumstances of the operation. Hide Caption 6 of 15 Photos: Notable leakers and whistle-blowers Tobacco industry executive Jeffrey Wigand issued a memo to his company in 1992 about his concerns regarding tobacco additives. He was fired in March 1993 and subsequently contacted by "60 Minutes" and persuaded to tell his story on CBS. He claimed that Brown & Williamson knowingly used additives that were carcinogenic and addictive and spent millions covering it up. He also testified in a landmark case in Mississippi that resulted in a $246 billion settlement from the tobacco industry. Wigand has received public recognition for his actions and continues to crusade against Big Tobacco. He was portrayed by Russell Crowe in the 1999 film " The Insider ." Hide Caption 7 of 15 Photos: Notable leakers and whistle-blowers For 10 years, Frederic Whitehurst complained mostly in vain about practices at the FBI's world-renowned crime lab, where he worked. His efforts eventually led to a 1997 investigation that found lab agents produced inaccurate and scientifically flawed testimony in major cases, including the Oklahoma City and World Trade Center bombings. The Justice Department recommended major reforms but also criticized Whitehurst for "overstated and incendiary" allegations. He also faced disciplinary action for refusing to cooperate with an investigation into how some of his allegations were leaked to a magazine. After a yearlong paid suspension he left the bureau in 1998 with a settlement worth more than $1.16 million. Hide Caption 8 of 15 Photos: Notable leakers and whistle-blowers FBI whistle-blower Coleen Rowley accused the bureau of hindering efforts to investigate a suspected terrorist that could have disrupted plans for the September 11, 2001, terror attacks. In 2002 she fired off a 13-page letter to FBI Director Robert Mueller and flew to Washington to hand-deliver copies to two members of the Senate Intelligence Committee and meet with committee staffers. The letter accused the bureau of deliberately undermining requests to look into Zacarias Moussaoui , the only person convicted in the United States of playing a role in the attacks. She testified in front of Congress and the 9/11 Commission about the FBI's mishandling of information. Rowley was selected as one of Time magazine's People of the Year in 2002 , along with whistle-blowers Sherron Watkins of Enron and Cynthia Cooper of WorldCom. Hide Caption 9 of 15 Photos: Notable leakers and whistle-blowers Sherron Watkins, a former vice president at Enron, sent an anonymous letter to founder Kenneth Lay in 2001 warning him the company had accounting irregularities. The memo eventually reached the public and she later testified before Congress about her concerns and the company's wrongdoings. More than 4,000 Enron employees lost their jobs, and many also lost their life savings, when the energy giant declared bankruptcy in 2001. Investors lost billions of dollars. An investigation in 2002 found that Enron executives reaped millions of dollars from off-the-books partnerships and violated basic rules of accounting and ethics. Many were sentenced to prison for their roles in the Enron scandal Hide Caption 10 of 15 Photos: Notable leakers and whistle-blowers Cynthia Cooper and her team of auditors uncovered massive fraud at WorldCom in 2002. They found that the long-distance telephone provider had used $3.8 billion in questionable accounting entries to inflate earnings over the past five quarters. By the end of 2003, the total fraud was estimated to be $11 billion. The company filed for bankruptcy protection and five executives ended up in prison. Cooper started her own consulting firm and told her story in the book "Extraordinary Circumstances: The Journey of a Corporate Whistleblower." Hide Caption 11 of 15 Photos: Notable leakers and whistle-blowers In 2003, federal air marshal Robert MacLean anonymously tipped off an MSNBC reporter that because of budget concerns, the TSA was temporarily suspending missions that would require marshals to stay in hotels just days after they were briefed about a new "potential plot" to hijack U.S. airliners. The news caused an immediate uproar on Capitol Hill and the TSA retreated, withdrawing the scheduling cuts before they went into effect. MacLean was later investigated and fired for the unauthorized disclosure of "sensitive security information." Hide Caption 12 of 15 Photos: Notable leakers and whistle-blowers Joe Darby is the whistle-blower behind the Abu Ghraib prison abuse scandal in Iraq. He says he asked Army Reserve Spc. Charles Graner Jr. for photos from their travels so he could share them with family. Instead, he was given photos of prisoner abuse. Darby eventually alerted the U.S. military command, triggering an investigation and global outrage when the scandal came to light in 2004. Graner was sentenced to 10 years in prison for his part in the abuse. He was released in 2011 after serving 6½ years of his sentence. The military and members of Darby's own family ostracized him, calling him a traitor. Eventually he and his wife had to enter protective custody. Hide Caption 13 of 15 Photos: Notable leakers and whistle-blowers The New York Times reported in 2005 that in the months after the September 11, 2001, attacks, President George W. Bush authorized the U.S. National Security Agency to eavesdrop without a court warrant on people in the United States, including American citizens, suspected of communicating with al Qaeda members overseas. The Bush administration staunchly defended the controversial surveillance program. Russ Tice, an NSA insider, came forward as one of the anonymous sources used by the Times. He said he was concerned about alleged abuses and a lack of oversight. Here, President Bush participates in a conversation about the Patriot Act in Buffalo, New York, in April 2004. Hide Caption 14 of 15 Photos: Notable leakers and whistle-blowers Army Pfc. Bradley Manning was convicted July 30 of stealing and disseminating 750,000 pages of classified documents and videos to WikiLeaks, and the counts against him included violations of the Espionage Act. He was found guilty of 20 of the 22 charges but acquitted of the most serious charge -- aiding the enemy. Manning is set to speak in his defense when he takes the stand during the sentencing phase of his court-martial on Wednesday, August 14. He could face up to 90 years in prison if the judge imposes the maximum sentence. Hide Caption 15 of 15

The article cites documents prepared by the National Counterterrorism Center dated August 2013, which is after Snowden left the United States to avoid criminal charges.

Greenwald has suggested there was another leaker. In July, he said on Twitter "it seems clear at this point" that there was another.

Government officials have been investigating to find out that identity.

In a February interview with CNN's Reliable Sources, Greenwald said: "I definitely think it's fair to say that there are people who have been inspired by Edward Snowden's courage and by the great good and virtue that it has achieved."

He added, "I have no doubt there will be other sources inside the government who see extreme wrongdoing who are inspired by Edward Snowden."

It's not yet clear how many documents the new leaker has shared and how much damage it may cause.

So far, the documents shared by the new leaker are labeled "Secret" and "NOFORN," which means it isn't to be shared with foreign government.

That's a lower level of classification than most of the documents leaked by Snowden.

Government officials say he stole 1.7 million classified documents, many of which were labeled "Top Secret," a higher classification for the government's most important secrets.

Big databases

The biggest database, called the Terrorist Identities Datamart Environment, now has 1 million names, a U.S. official confirmed to CNN.

That's boosted from half that many in the aftermath of the botched attempt by the so-called underwear bomber to blow up a U.S.-bound jetliner on Christmas Day in 2009.

The growth of TIDE, and other more specialized terrorist databases and watchlists, was a result of vulnerabilities exposed in the 2009 underwear plot, government officials said.

The underwear bomber, Umar Farouk Abdulmuttalab, was not on government watchlists that would have prevented him from being allowed to fly to the United States.

In 2012, the National Counterterrorism Center reported that the TIDE database contained 875,000 names. There were about 500,000 in 2009 before the underwear bomb plot.

The Intercept first reported the new TIDE database numbers, along with details of other databases.

As of November, 2013, there were 700,000 people listed in the Terrorist Screening Database (TSDB), or the "Terrorist Watchlist, according to a U.S. official. Fewer than 1% are U.S. persons and fewer than 0.5% are U.S. citizens.

The list has grown somewhat since that time, but is nowhere near the 1.5 million figure cited in recent news reports. Current numbers for the TSDB cannot be released at this time.

The Intercept report said, citing the documents, that 40% on the "Terrorist Watchlist" aren't affiliated with terror groups.

U.S. officials familiar with the matter say the claim is incorrect based on a misreading of the documents.

Americans on lists

The report said that as of August, 2013, 5,000 Americans were on the TSD watchlist. Another 15,800 were on the wider TIDE list.

A smaller subset, 16,000 names, including 1,200 belonging to Americans, are listed as "selectees" who are subject to more intensive screening at airports and border crossings.

According to the Intercept, citing the documents, the cities with the most names on the list are: New York, Dearborn, Michigan; Houston; San Diego; and Chicago. Dearborn is home to one the nation's biggest concentrations of Arab and Muslim populations.

According to the documents cited by the Intercept, the government has also begun a new effort to collect information and biometric data on U.S. persons in the aftermath of the 2013 Boston Marathon bombings.

The data includes photos from driver's licenses. That effort likely was spurred by the fact that FBI agents investigating the Boston bombings found existing databases lacking when they tried to match images of the two bombers isolated from surveillance video, according to U.S. officials familiar with the matter.

Stored on Pentagon system

Documents classified as "Secret" are stored on a Pentagon-operated computer system called SIPRNet, which the Defense and State departments use to share classified information.

A recent Government Accountability Office study found that between 2006-2011 there were 3.2 million approved by the Pentagon to handle secret, top secret, SCI (sensitive compartmented) information.

SIPRnet is one of the computer systems that the former Army soldier now known as Chelsea Manning accessed to leak hundreds of thousands documents, including State Department cables.

The Manning leak was the largest U.S. intelligence leak until Snowden.