North Korea's recent proclamations of aggression could be a sign of frustration at what it views as "failed diplomacy," said an expert on Monday.
On Saturday, North Korea issued a warning of retaliatory military measures against South Korea.
"By exercising my power authorized by the Supreme Leader, our Party and the state, I gave an instruction to the ... department in charge of the affairs with (the) enemy to decisively carry out the next action," said Kim Yo Jong, who serves unofficially as one of North Korean leader Kim Jong Un's top aides, according to a statement carried by state news agency KCNA obtained by NBC News. Kim Yo Jong is the younger sister of Kim Jong Un.
Pyongyang has been angered by defectors who have been sending rice and anti-North propaganda leaflets — typically via balloons or in bottles by sea.
The balloons and rice have been standing issues between the two countries, but the context in which Pyongyang is now operating in is quite different, so the recent developments need to be seen in a "broader context of frustration," said John Park, director of the Korea Project at the Harvard Kennedy School.
"We're in the long shadow of what the North Koreans view to be failed diplomacy at the leader-to-leader level," said Park.
Pyongyang is moving in a different direction because the North Koreans feel they have been let down by the U.S. and South Korea. And it comes two years after the historic summit in Singapore in June 2018, between Kim and U.S. President Donald Trump, said Park.
There has been little progress since, and a second round of talks ended abruptly in the Vietnamese capital of Hanoi when both sides could not agree on the removal of sanctions.
On Saturday, the younger Kim also threatened the destruction of a joint liaison office at the Kaesong industrial zone, "invoking the authority of her brother to order the military of North Korea to prepare for possible military action against what we believe to be the inter-Korean liaison office," noted Park.
"Certainly it would be high in symbolism but the message would be very clear to South Korea — that all of the progress from the inter-Korean agreement would be gone from the eyes of North Korean side," said Park.
Kim met South Korean President Moon Jae-in at least three times in 2018, ushering hope of warming ties and possible reconciliation between the two. Both countries are currently still technically at war since the 1950-1953 Korean War ended in a ceasefire, instead of a peace treaty.
Moon's administration has sought to discourage the leaflet and rice campaigns, Reuters reported.
The fact that the North Korean leader's younger sister is issuing statements lends credence to her role.
"We're seeing a lot of big statements coming out of Kim Yo Jong," said Park. This indicates that her role is not just ceremonial and that she has been "chronically underestimated," he added.
"I think what we're seeing now is essentially a reflection of a partnership that she has with her brother," said Park. "It looks like there is this kind of power partnership between the two that became more visible."
The younger Kim playing a larger role in the public domain comes as concerns brew over the health of the elder Kim, who disappeared from public view at one point of time fueling concerns he was ill. He eventually emerged again, after weeks of speculation over his health.