That clearly marks Choe as the No. 2 man now.

Besides his top military post, Choe is also a member of the Presidium of the Workers Party Politburo. Only four officials are members of the Politburo Presidium -- two others are Kim Jong-un and Kim Yong-nam, the titular head of state, and experts believe the fourth slot has been handed over from ex-premier Choe Yong-rim to Premier Pak Bong-ju.

Sources on Wednesday claimed former leader Kim Jong-il asked Choe on his deathbed to help his son Jong-un.

Since the execution of leader Kim Jong-un's uncle Jang Song-taek, the most prominent official in the North has been Choe Ryong-hae, the chief of the military Politburo. But it is unclear whether Choe now pulls the strings or whether he is just a stuffed shirt and will prove expendable in the medium to long term.

Ko Yong-hwan of the Institute for National Security Strategy, a former North Korean diplomat, has described Choe Ryong-hae a "foolhardy daredevil."

"Choe is thought to be a man who would go through fire and water to grab power and do anything to maintain it," Ko said.

But Choe could be tainted by his association with Jang. Choe's elder brother was a close friend of Jang's and sources recall that Choe once knelt before Jang, and that the two secretly met for drinks.

According to sources, it was Jang who asked Kim Jong-il to reinstate Choe when he had been demoted. But when Jang was in trouble, Choe was either unable to save him or turned his back.

Choe is likely to tread carefully for the time being because he saw what happened to Jang.

"Choe Ryong-hae suffered a lot after he was dismissed from the chairmanship of the Socialist Youth League in the wake of a scandal in 1998," one source said. "He'll keep a low profile and remain loyal to the regime because he knows what happens if he loses power."

Some pundits speculate that Choe will be next to be purged, like former Army chief Ri Yong-ho or Jang Song-taek.

Although a low-ranking Army officer, Choe was a long-term senior official in the Socialist Youth League and the party and has no significant military background.

He seems to have been appointed to head the military Politburo only because of the close personal relationship between his father, former armed forces minister Choe Hyon, and the Kim family.

The military reportedly disapproves of Choe due to the frequent personnel reshuffles among top brass since Kim Jong-un took power. The fact that the purge of Army chief Ri Yong-ho in July was led by the party rather than the military indicates Choe’s lack of influence in the army, according to experts.

Park Hyung-joong of the Korea I nstitute for National Unification said it is likely that the military will plot to put Choe out of action.

"For the time being, Choe Ryong-hae's position is getting stronger and Kim Jong-un's dependence on him will increase," said Chung Sung-jang of the Sejong Institute. "But he could be purged if he makes a misstep and Kim sees him as a threat."