Kim Jong-un has once again proved to the North Korean elite he is indeed the "iron fist in the iron glove" by executing a top general.

Totalitarian dictator Kim put ordered the execution of General Pyon In Son for failing to heed orders to shake up the diplomatic staff which handles relations with China. North Korea is reportedly loosening ties with Beijing and moving closer to Russia.

North Korea observers declared the death of Pyon after the four-star general was not seen in public for months. His death has been interpreted as a power play by the podgy ruler to enforce obedience in the military.

"The purge of Pyon sends a message that helps to discipline the military," said Seoul professor Kim Yong Hyun. "The execution is a symbol that will help tighten loyalty."

But Pyon In Son's execution has yet to be confirmed by Pyongyang, cautioned South Korea's Unification Ministry.

Spokesman Lim Byeong Cheol said: "It's true that (Pyon) has not been seen in public since Nov. 5 last year but whether he was purged or not has not been confirmed."

General Pyon was seen as a rising star inside North Korea, having been promoted from obscurity late in 2013.

North Korea has also made headlines for a blood-curdling verbal blast at the United State, branding it a "cesspool" and threatening nuclear war with its sworn enemy.