Why did Kim Jong-un turn on his uncle and mentor?

Almost two years ago to the day Jang Song-thaek was walking solemnly just behind his nephew with his hand on the hearse carrying the coffin of Kim Jung Il, his brother-in-law.

Jang's closeness to the political elite and ruling family was clear, he appeared to be the power behind the throne of the new young leader. The older trusted family member was seen as the guide for Kim Jong-un, as he continued control of the world's only communist dynasty.

Now it appears that his young nephew has turned on his mentor and had him executed, shot with a heavy machine gun according to some reports, for attempting to overthrow the state.

Mr Jang was "worse than a dog" said the state news agency despite once holding senior positions in the ruling party and military.

No outsider can really claim to know what goes on within the power struggles of the murky, factional and secretive North Korean elite. However, the consensus from South Korean observers and Western diplomats is that Jang was more inclined to adopt the economic reforms which China adopted following the fall of the Soviet Union. Any official reform can also be seen as criticism of a regime which has failed economically.

The collapse of North Korea's economy after the end of soviet subsidies is covered up by rosy propaganda - the West blamed for undermining a socialist utopia. Any criticism, direct or implied, in North Korea can be deemed counter revolutionary and that's a very, very dangerous charge to face. Jang was found guilty of being a counter revolutionary and execution was carried out immediately, according to North Korean state media.

When Jang was dramatically arrested by armed soldiers during a party meeting earlier this week he was accused of "double dealing", begging the question dealing with who?Was a deal with the Chinese to push his nephew into loosening up the economy. Jang would occasionally be sent to Beijing to meet China's top leaders. There was certainly communication.

Kim Jong-un on the other hand, hasn't yet visited the Chinese capital, at least as far as we know. Economic reform would mean drastic changes in the political structures within North Korea. Now the military receives the largest share of whatever money the leadership can make in a country where the economy is stagnant and broken.

The North Korean leadership stands accused by the West of selling missile technology, manufacturing counterfeit currency and making crystal meth to sell abroad. It has the fourth largest army in the world with a 23 million population, which relies on international food aid.

So interpretations are; that vested interests within the military have reacted badly to moves to open up the economy to China. Hardliners would see that as a sign of defeat and gift to Western critics of a regime too stubborn to ever admit it's wrong.

That Kim Jong-un is continuing to consolidate his power and show his strength to anyone thinking of questioning his authority. Killing a family member and senior Party official sends a vicious message to anyone who might think that the young leader hasn't learnt from the brutal past lessons of Stalinist power struggles.