Pyongyang, North Korea ? North Korea has tightened internal security and put troops on alert since the announcement of leader Kim Jong Il’s death as it moves to consolidate power behind his young son and heir, South Korean intelligence indicated today.

Concerns over what will happen next in the unpredictable communist enclave — which has a 1.2-million troop military, advanced ballistic missiles and a nuclear weapons development program — have sharply raised tensions around northeast Asia.

But South Korean parliament member Kwon Young-se said Seoul’s National Intelligence Service believes the North is now concentrating on consolidating Kim Jong Un’s power and the country has placed its troops on alert since Kim Jong Il’s death. North Korea on Monday announced Kim, 69, died of a massive heart attack.

Kwon said the NIS has told the parliamentary intelligence committee, which he chairs, that senior military officials have pledged allegiance to Kim Jong Un, but police security has been tightened in major cities across the country. Officials in Seoul say they have not seen any unusual military troop movements.

Initial indications coming out of North Korea suggest the transition to Kim Jong Un was moving forward.

The young Kim, still in his twenties, led a procession of senior officials Tuesday in a viewing of Kim Jong Il’s body, which is being displayed in a glass coffin near that of Kim Il Sung.

Publicly presiding over the funeral proceedings was important for Kim’s son, strengthening his image as the country’s political face.