(CNN) -- North Korea for the first time publicly specified the "hostile acts" that landed Kenneth Bae a 15-year sentence at a labor camp.

The Korean-American tour operator set up anti-North Korean bases in China and distributed anti-regime literature, a spokesman for the North Korean Supreme Court told the state-run KCNA news agency.

"He committed such hostile acts as egging citizens of the DPRK overseas and foreigners on to perpetrate hostile acts to bring down its government while conducting a malignant smear campaign against it," the court said, using the acronym of the country's official name, the Democratic People's Republic of Korea.

Bae, who the North Koreans refer to as Pae Jun Ho, was arrested November 3 after arriving as a tourist in Rason city, a port in the northeastern corner of North Korea.

He was later sentenced, but authorities until now had not elaborated on what he was accused of.

Bae was "caught red-handed" when he entered Rason City with anti-North Korea literature, the court said.

He was accused of preaching at churches and lecturing to groups about the need to escalate confrontation, the court said.

The statement said that the court did not allow Bae to have an attorney after he refused to give a plea, as North Korean law instructs.

Bae confessed to his crimes, the court said, according to KCNA, and "they were clearly proved in an objective manner by evidence and testimonies."

In previous instances, North Korea has released Americans in its custody after a visit by some U.S. dignitary -- in recent cases, former Presidents Jimmy Carter and Bill Clinton.

But Bae's case could get caught up in the recent tensions between North Korea and the United States.

The news comes on the heels of weeks of superheated rhetoric from North Korea, which conducted its third nuclear test in February and launched a satellite into orbit atop a long-range rocket in December. Washington responded by deploying additional missile interceptors on the West Coast, dispatching a missile defense system to the Pacific territory of Guam and bolstering annual U.S.-South Korean military exercises with overflights by nuclear-capable B-2 and B-52 bombers.

But the intensity of the North's rhetoric appears to have subsided recently, and the U.S.-South Korean drills finished this week, removing another source of friction.

CNN's Dana Ford, Jethro Mullen and K.J. Kwon contributed to this report.