North Korean leader Kim Jong Un has described his once-powerful uncle and mentor, whom he purged and executed, as "factionalist filth" in a new year message in which he boasted of a surge of internal strength.
Kim's comments, including those focusing on one of the biggest political developments in Pyongyang in years, and certainly since the young leader took power two years ago, will be closely scrutinised by outside analysts and governments for clues about the reclusive communist country's intentions and policy goals.
North Korea's "resolute" action to "eliminate factionalist filth" within the ruling Workers' Party has bolstered the country's unity "by 100 times," Kim said in the speech broadcast by state TV.
Analysts are divided about what Jang Song Thaek's execution on treason charges means, but many believe it shows Kim Jong Un has yet to establish the same absolute power that his father and grandfather enjoyed. Jang was widely considered the country's number two power.
Officials in Seoul say potential instability in the North could lead to the country launching provocative action against South Korea to help consolidate internal unity.
Attacks blamed on North Korea killed 50 South Koreans in 2010, and tension on the Korean Peninsula still lingers, although Pyongyang has backed away from war rhetoric from early last year that included threats of nuclear attacks against Washington and Seoul.
North Korea has also vowed to restart nuclear bomb fuel production. The country conducted its third nuclear test in February and is estimated to have a handful of crude nuclear devices and to be working toward building a warhead small enough to mount on a long-range missile. Most experts say that goal may take years to achieve.
The rival Koreas share one of the world's most heavily armed borders, with hundreds of thousands of combat-ready troops facing each other along the mine-strewn Demilitarised Zone.
The 1950-53 Korean War ended with an armistice, not a peace treaty, leaving the peninsula technically in a state of war. About 28,500 American troops are deployed in South Korea to help deter North Korean aggression.
During his two years in power, Kim Jong Un has overseen nuclear and missile tests, other high-profile purges and a barrage of threats. His father Kim Jong Il took a much more low-profile approach when he took over after his father and the country's founder Kim Il Sung's death in 1994.
Kim Jong Un, who also spoke publicly last New Year's Day, appears to be following in his grandfather's steps.
Kim Il Sung gave public New Year's readings on state television and radio. Under the more private Kim Jong Il, the North's leading newspapers released the annual statement in a joint editorial.