SEOUL, South Korea (CNN) -- Kim Jong Un issued his first military orders as leader of North Korea just before the death of his father was announced, a South Korean state-run news agency said Wednesday.

Citing "a South Korean source," Yonhap reported that Kim "ordered all military units to halt field exercises and training and return to their bases."

The source called it a sign that Kim Jong Il's son, believed to be in his late 20s, had taken "complete control over the military," Yonhap reported.

An intelligence official said North Korea may be trying to prevent attempted defections as the country goes through a tumultuous transition, the report said.

In Seoul, questions have been raised over why South Korean intelligence was apparently unaware of Kim Jong Il's death until the official announcement.

North Koreans know little of Kim Jong Un

Kim Jong Un revealed

Both Won Sei Hoon, who heads South Korea's National Intelligence Service, and Defense Minister Kim Kwan Jim "came under fire" after admitting they learned of the death from TV news coverage, Yonhap reported.

Just over the border in Dandong, China, CNN spoke with a defector who was scared of North Korean spies watching him.

"North Koreans don't speak openly," the man said. "If anyone knows I'm talking, I would be sent to prison and there's no mercy there. I would be shot dead."

He painted a grim picture of life in North Korea, where he said people are starving, aid is scarce, and the only operating factories serve the military.

"Pig feed, that's all we can eat," he says, adding, "There is no food, not even food from China. It's been blocked for three years."

His son and daughter remain inside North Korea. He crosses back and forth every six months to keep his family alive.

He told CNN he fears a desperate country with a potential power vacuum that could lash out.

Before Kim Jong Il died, "he was preparing the country for war and death, and to hand power to Kim Jong Un," the man said.

Other North Koreans in Dandong were openly weeping over the death of their "dear leader," as he was called in his country.

North Korean state-run news agency KCNA, meanwhile, carried messages praising Kim Jong Il. The top story on the agency's English language website Wednesday, dated Tuesday, said Kim Jong Il "dedicated himself to the happiness of the people all his life."

"He had a noble wish," the KCNA report said. "It was to bring the greatest happiness and honor to the people even if he had plucked a star from the sky and grown flowers even on a rock."