HALIFAX -- A Canadian naval officer pleaded guilty to espionage Wednesday, five years after a Crown lawyer said he walked into the Russian embassy, offered up military secrets for money and began a relationship that resulted in the sharing of a "vast amount" of sensitive information.

Sub-Lt. Jeffrey Paul Delisle rose before a provincial court judge in Halifax, showing no emotion as he clasped his hands together, to acknowledge that he understood the consequences of his pleas to the unprecedented charges.

When asked if he confirmed the guilty pleas, the 41-year-old threat assessment analyst merely said, "Yes sir," before leaving the court to return to prison as he awaits sentencing in January.

The surprising development came more than six months after federal Crown attorney Lyne Decarie outlined the case against Delisle during a bail hearing on March 28, saying he voluntarily approached Russian officials in 2007.

There was a publication ban on evidence and arguments presented at the proceedings in the spring, but the guilty plea means there will not be a jury trial now. Sentencing is scheduled for Jan. 10.

There has been no agreed statement of facts in the case.

At the bail hearing, Decarie said in court that "following some personal problems, Delisle walked into the Russian embassy in Ottawa and offered his services. He offered to sell information to them."

Decarie read in court portions of a statement she said Delisle gave to police. She said he asked to speak with a security officer at the embassy.

"I showed them my ID card and they asked me a bunch of questions, took my name and off I go," said Decarie, reading from Delisle's statement to police after he was arrested last Jan. 13.

Delisle worked at Trinity -- the name for the military's intelligence centre on the East Coast -- which experts have said would provide tactical assessments primarily to Canadian warships and aircraft, both at home and overseas.

Decarie said in court that Delisle would have access to the facility's secure and unsecured systems that contained information about Canada and its allies.

Most of what he shared related to the military, Decarie alleged, but it also included material about organized crime, political players and the Chief of Defence phone and contact list -- something she described as a "who's who of military personnel" with email addresses and phone numbers.

Delisle, who joined the navy as a reservist in 1996, became a member of the regular forces in 2001 and was promoted to an officer rank in 2008. He had access to systems with information shared by the Five Eyes community that includes Canada, the United States, Britain, Australia and New Zealand.

In damage assessments read in court, officials in the Canadian intelligence community said the breaches from 2007 to 2012 could unmask intelligence sources and place a chill on the sharing of vital security information.

"Delisle put into jeopardy the identity of the confidential sources of information and the means by which the (Canadian Security Intelligence Service) collects information," one official wrote in a statement read by Decarie.

"Delisle's unauthorized disclosure to the Russians since 2007 has caused severe and irreparable damage to Canadian interests."

The statements conflict with the appraisal Defence Minister Peter MacKay gave soon after Delisle was arrested when he said "our allies have full confidence in Canada."

The Crown gave a detailed accounting of how it alleged Delisle transmitted the information from the intelligence centre in downtown Halifax to his home and then on to Russian agents.

Decarie said Delisle was asked to search for Russian references on his work computer, transfer it to a USB key and take it to his home nearby.

He would then provide it to the Russians by pasting it into an email program that he shared with his foreign handler, she said.

Decarie said Delisle, a father who is divorced from his first wife, received $5,000 for the first couple of transfers after July 2007 and then $3,000 every month.

He came to the attention of the authorities when he was returning from a trip to Brazil to meet a Russian agent in the fall of 2011, Decarie said. He was carrying several thousand dollars and pre-paid credit cards, and had changed his hotel twice in the community where he stayed for five days, raising the suspicions of the Canada Border Services Agency.

The Crown said some time after, the RCMP took over the account he shared with the Russians, allowing Delisle to think he was transmitting material to a Russian agent when "it was actually the RCMP opening the email."

His role appeared to change after he was stopped at the border, with the Russians telling him he should "go to sleep for the rest of the year" and would become "the pigeon" or liaison between all of the agents in Canada.

But Decarie said his transfers slowed only briefly after his return from Brazil and that he leaked information in November and December of 2011, and, in one of the last transfers of information, on Jan. 11, 2012, when he posted 28 pages he had taken from his work computer.

Delisle was arrested two days later in Halifax and charged with one count of breach of trust under the Criminal Code and two charges of passing information to a foreign entity that could harm Canada's interests under the Security of Information Act.

He is the first person in Canada to be charged and convicted under the security act, which was passed by the Commons after the 9-11 terrorist attacks on the United States.

In court at the bail hearing, Decarie read portions of a police statement where Delisle reportedly described the day he walked into the embassy as "professional suicide."

"The day I flipped sides ... from that day on, that was the end of my days as Jeff Delisle," Decarie read from his statement.

She said he claimed to police that his betrayal was for ideological reasons and that he wasn't doing it for the money.

But Decarie said Delisle, who also worked for the military in Ottawa and Kingston, Ont., went on to tell officers that the Russians had pictures of his children.

"They had all my information. They had photos of me," Decarie read from Delisle's statement. "They had photos of my children and I knew exactly what it was for."

Defence lawyer Mike Taylor said his client decided about a week ago to end the matter that captivated the intelligence community and raised uneasy questions about the effect any leaked material might have on Canada's relations with its closest allies.

"He's just wants to move forward, he wants to get it done, put it behind him, accept his responsibility and have the court deal with it," Taylor said outside court after what was supposed to be the start of Delisle's preliminary hearing.

"This was simply a matter of deciding there's no good reason to simply put on a show for the public, to go through the motion when, in my estimation, the outcome was clear and Mr. Delisle was realistic about that."

Decarie would not say what sentence she will seek. But she said the breach of trust charge under the Criminal Code carries a maximum sentence of five years, while the other two charges under the security act carry life sentences.

Taylor said no deal was made with the Crown on possible sentences, adding that the Crown was asking for "significant numbers" in a federal institution, but not a life sentence.