Army Pfc. Bradley Manning should spend 60 years in prison because he betrayed the U.S. by giving classified material to WikiLeaks, a prosecutor said Monday.

The soldier’s defense attorney didn’t recommend a specific punishment, but suggested any prison term shouldn’t exceed 25 years because the classification of some of the documents Manning leaked expires in 25 years.

Defense attorney David Coombs said Manning, who was 21 when he enlisted in 2007, had limited experience in life and in the military. His youthful idealism contributed to his belief that he could change the way the world viewed the wars in Iraq and Afghanistan, and all future wars, by leaking the secret files, Coombs said.

“He had pure intentions at the time that he committed his offenses,” Coombs said. “At that time, Pfc. Manning really, truly, genuinely believed that this information could make a difference.”

Manning faces up to 90 years in prison, but Capt. Joe Morrow only asked the judge to sentence him to 60. Morrow did not say during closing arguments of the court-martial why prosecutors were not seeking the maximum punishment.

A military judge convicted Manning last month of 20 offenses, including six violations of the Espionage Act and five counts of stealing protected information.

“He’s been convicted of serious crimes,” Morrow said. “He betrayed the United States and for that betrayal, he deserves to spend the majority of his remaining life in confinement.”

Coombs said the government’s proposed sentence means the prosecution is only interested in punishment — having Manning “rotting in a jail cell” — and does not include the element of rehabilitation. He urged the judge to hand down a sentence that “allows him to have a life” one day.

The judge, Col. Denise Lind, said she will begin deliberating the punishment today.

The prosecutors’ request for 60 years likely reflects their view that Manning’s offenses were less egregious than if he had specifically sought out foreign agents and given them information, said Michael Navarre, a former Navy judge advocate in private practice in Washington.

The government was unable to show that Manning knew the documents would get to al-Qaida, and Manning has said he only leaked information that he believed would not be harmful.

Retired Army Col. Lisa Windsor, a military lawyer in private practice in Albany, N.Y., said prosecutors asked for what they likely consider a realistic sentence. Besides, she said, “60 years in prison is pretty horrible.”

The 25-year-old native of Crescent, Okla., leaked more than 700,000 documents, including Iraq and Afghanistan battlefield reports and State Department diplomatic cables, while working in early 2010 as an intelligence analyst in Iraq. He also leaked video of a 2007 U.S. Apache helicopter attack in Baghdad that killed at least nine people, including a Reuters news photographer and his driver.

Manning took the stand last week and apologized for hurting his country, pleading with the judge for a chance to go to college and become a productive citizen.

Family members and a psychologist testified for the defense, saying the soldier felt extreme mental pressure in the military because of his gender-identity disorder during the “don’t ask, don’t tell” era.

Prosecutors have called Manning an anarchist computer hacker and attention-seeking traitor. The soldier’s supporters have hailed Manning as a whistleblower.

Prosecutors also asked the judge to fine Manning $100,000, reduce his rank to private and give him a dishonorable discharge.