North Korean leader Kim Jong Un visited the mausoleum of his grandfather, Kim Il Sung, on Tuesday, the 102nd birth anniversary of the country's late founding leader.
The anniversary, known as the Day of the Sun, is a major holiday for North Koreans. Many gather to pledge their loyalty and pay respects at portraits or statues of the leader.
State television showed Kim Jong Un, accompanied by senior military officials, at Pyongyang's Kumsusan Palace, where the embalmed body of his grandfather is displayed.
The body of Kim's father and predecessor, Kim Jong Il, also lies in state at the palace. The three generations of Kim leaders hold an almost God-like status in North Korea.
Meanwhile, protesters burned and trampled on pictures of the three Kims during an anti-North Korea protest in Seoul.
One of the protesters, Park Chan-sung, called for more sanctions against Pyongyang, which he said is a threat to the international community.
"North Korea has fired missiles into the East Sea and it is reportedly preparing a fourth nuclear test now. Our South Korean people strongly condemn the North's dictatorship on the birthday of Kim Il Sung, 'The Day of Sun,'" said Park.
At South Korea's defense ministry, spokesman Kim Min-Seok said the North's celebrations appeared to be less elaborate than in past years, when the day served as a show of military strength.
"It seems that North Korea is not preparing for any large-scale military parade. Also, the possibility for North Korea's large-scale firing demonstration is not that high at this point. Even though it can sporadically take place. However, it is understood that North Korea is ready to launch missiles at any time, so South Korean and the U.S. intelligence agencies are keeping close watch and tracing any missile movements," said Kim.
Tensions are high following a series of North Korean rocket and missile tests last month. On March 31, the two Koreas also exchanged artillery fire into one another's waters.
Following the exchange, South Korean officials found a crudely built, unmanned and unarmed aircraft in the area. They later revealed that two other drones had been found.
Seoul believes the drones belong to North Korea. Pyongyang denied the charge, offering to assist in a South Korean government investigation into who was responsible.
On Tuesday, South Korea's defense ministry rejected the offer, saying it is "not worth considering" and is part of a "psychological war" against the South.
The developments come as United States and South Korean troops prepare to end their annual large-scale, joint military drill, known as Foal Eagle, which began in February.
Washington and Seoul say the exercise is defensive in nature, but North Korea says it views the drills as preparation to invade.