“I can’t recall having someone ever stealing secrets from the executive office of the president,” Roger Cressey, a former member of the National Security Council and top counter-terror expert during the Clinton Administration, told the Star-Ledger’s Washington bureau.

“The bottom line is there is an inherent level of trust that comes with any person who works at the White House and, if individuals are so inclined, they can violate that trust,” said Cressey. “Even with a highly selective screening process, there are no guarantees.”

Aragoncillo pleaded guilty in Newark on May 4 to federal charges of passing top secret and secret information to Philippine opposition leaders when he worked from 1999 to 2002 as a staff assistant to military advisers in the vice presidential offices of Al Gore and Dick Cheney, and later as an FBI intelligence analyst in New Jersey.

Prosecutors said his aim was to help topple Philippine President Gloria Macapagal-Arroyo.

James Bamford, the author of two books on the secretive National Security Agency, said Aragoncillo’s case is “as far as I know the first time somebody who worked in the White House has actually been convicted of espionage.”

“There have been cases where people in the White House passed on information for domestic political reasons but not for a foreign country,” Bamford said. “I guess you would have to question the hiring practices at the White House.”

While unsure how much information Aragoncillo stole, Cressey said the “good news is that what he passed along to the opposition probably had no real effect, and whatever intent he had to help the opposition overthrow the government failed.”

“The second point is he got caught and is going to jail, and that is not insignificant,” said Cressey.

While swiping top secret documents from the White House may be a unique case, Aragoncillo is hardly the first or the most damaging spy to have slipped through the security cracks while working for the U.S. Government. There have been spies inside the Central Intelligence Agency, the FBI, National Security Agency and the Pentagon.

Some of the most notorious cases include:

• Robert Philip Hanssen, a high level FBI agent arrested in 2001 and later convicted of selling American secrets to Moscow for $1.4 million in cash and diamonds over a 15-year period. Officials said his treason was the “worst intelligence disaster in U.S. history.”

• Aldrich Ames, a CIA counterintelligence officer and analyst convicted in 1994 of selling U.S. secrets to the Soviet KGB for a decade. He was paid some $2.7 million. Ames’ information betrayed at least 30 sources, 10 of whom were later executed by the Soviets.

• Jonathan Pollard, a civilian intelligence officer with the Navy who was paid tens of thousands of dollars to spy for Israel, and was sentenced to life in prison in 1987 for supplying national intelligence information to a foreign government.

• Ana Montes, the Pentagon’s top intelligence expert on Cuba, pleaded guilty in 2002 to spying for the Cuban Government for 16 years because she opposed U.S. policy toward Havana.

• Ronald William Pelton, a communications specialist with the NSA, was convicted in 1986 of spying for the Soviet Union. Authorities said he passed on highly classified information about U.S. intelligence collection locations to the Soviets.

In Aragoncillo’s case, he acknowledged pilfering documents on terrorism threats to U.S. interests in the Philippines, names of confidential government sources, situation reports on foreign countries and what he described as “a blueprint” for how to overthrow a government.

Some of the information had been designated “top secret,” the highest possible security classification, representing material that, if released, could gravely damage national security.

Aragoncillo said that he sent documents to his contacts while physically working at the vice president’s office, at the FBI and from his Woodbury home.

Prosecutors declined to characterize the impact of the espionage, other than to say it did not cause any deaths.

Aragoncillo said the information was shared with six other people, including former Philippine President Joseph Estrada and three legislators.

Together, they hoped to topple Mrs. Arroyo.

Though the allegations first surfaced last fall, the confession was still extraordinary. Its impact on diplomatic or defense matters was not immediately clear.

The White House declined to comment.

Wearing shackles and a green prison uniform, Aragoncillo, a Manila native, pleaded guilty before Senior U.S. District Judge William Walls to four charges, including transmitting national security secrets.

The espionage count carries a possible death sentence, but prosecutors agreed to recommend a penalty of roughly 15 to 20 years in prison.

Walls set sentencing for Aug. 14.

Aragoncillo did not comment during the proceeding and was led from the courtroom by U.S. marshals. His defense attorney later said that Aragoncillo, a naturalized U.S. citizen, was swayed by his feelings of loyalty to his homeland but never intended to harm the United States.

U.S. Attorney Christopher Christie dismissed the explanation.

“(Aragoncillo’s) betrayal is profound,” Christie said, “and a disservice to his country and all the men and women in the military and security positions around the globe who take the oath and serve with honor and integrity.”

The plea had been in the works since September, when Aragoncillo and Michael Ray Aquino, a Filipino living in New York, were arrested after the FBI determined Aragoncillo downloaded at least 100 documents from the Fort Monmouth Information Technology Center.

Court records showed that Aragoncillo immediately began negotiating with prosecutors.

Neither his attorney, First Assistant Federal Public Defender Chester Keller, nor the lead prosecutor, Assistant U.S. Attorney Karl Buch, would acknowledge any cooperation.

But in the last of 101 questions to the defendant at the hearing, Buch asked Aragoncillo if he was willing to provide more information about his co-conspirators and the coup plot.

Aragoncillo replied in the same crisp way he answered the previous 100 questions. “Yes, sir,” he said.

Aragoncillo had been a Marine for 16 years, rising to gunnery sergeant, when he began working in July 1999 as a staff assistant to military advisers in the office of Gore. At the time, he had “top secret” security clearance.

He met Estrada a year later, when the then-Philippine President visited the White House as part of an official state visit. Within months, prosecutors said, an unidentified legislator who accompanied Estrada on the trip contacted Aragoncillo, and asked him to begin supplying classified U.S. documents. Aragoncillo said he agreed.

Aragoncillo acknowledged that he continued to spy after he began working as an FBI analyst in 2004. He said he often passed information under an e-mail alias, “Juan Miguel,” and that he used code words.

“Bayside” meant the U.S. Embassy in Manila. “Young golfers” referred to Filipino army officers. Mrs. Arroyo was known as “the Penguin.”

In September, Aragoncillo stole a copy of a “secret” document outlining how to engineer a coup and set up a transitional government. He admitted e-mailing the document to a legislator who prosecutors have previously identified as Sen. Panfilo Lacson, a vocal Arroyo opponent.

“The attached info could be used as ‘guidance’ if and when you intend to install a military council and later transition to a ‘civilian cabinet,’” Aragoncillo wrote.

“I’ll print it because we are preparing something like this,” Lacson replied, according to Aragoncillo.

The case has roiled the Philippines, already known for corruption, particularly after prosecutors in Newark last month publicly named Estrada, Lacson and former Philippine House Speaker Arnulfo Fuentebella as unindicted co-conspirators. Each has denied any wrongdoing.

Aragoncillo’s guilty plea is expected to increase the pressure on Aquino, his co-defendant, who has rejected plea offers.

Prosecutors contend that Aquino, a former ranking officer in the Philippine National Police, was a conduit between Aragoncillo and Lacson.

The FBI began scrutinizing the two men after immigration officials detained Aquino last spring for overstaying his visa.

When Aragoncillo, identifying himself as a bureau employee, tried to intervene, immigration officers contacted the FBI.

Agents then began reviewing his work.