The seemingly endless appearances of "ghost ships" full of dead North Koreans on the shores of Japan is indicative of Kim Jong Un's weakening grip over his citizens, experts say.
The latest took place, when a capsized boat containing the decayed remains of seven bodies washed ashore in Kanazawa, a city on Japan's west coast.
A badge portraying former North Korean leaders Kim Il Sung and Kim Jong Il was also found nearby.
It was the second such discovery in Japan in January 2018.
The number of ghost ships — vessels discovered with no living crew — reached 104 in 2017, the highest since authorities started collecting data in 2013, Japan's Kyodo news agency quoted the national coast guard as saying.
Sea of Japan / East Sea between North Korea and Japan.
It remains unclear exactly who these people were, or why they showed up in Japan — experts have posited theories including food insecurity in North Korea, annual quotas imposed on fishermen, and a deal for fishing rights between North Korea and China.
A new theory suggested to Business Insider is that the increasing arrivals of these boats indicate Kim Jong Un's weakening grip over his country and its people.
It came from Professor Hazel Smith, a researcher at the School of African and Oriental Studies in London.
North Korea, notoriously, tightly controls its borders to prevent defections. Soldiers opened fire on one of their own who was caught in the act of defecting to South Korea in November 2017.
The army also plants landmines on various spots around its border — including the west coast — to prevent citizens from leaving and invaders from entering.
Smith, who lived in North Korea from 1998 to 2001, told Business Insider (BI):
"Security is disintegrating. There was always an incentive for people to get hold of a boat to try to fish and come back and sell it and make some money, but security was always extremely tight on the coasts.
"You had mined beaches, you had surveillance on the coast, so the fact that this is happening is not a surprise economically — people are taking the opportunities while they can — but what it shows also is the disintegration of the state's ability to stop people going out in boats."
She added that previously, obtaining boats was seen as a highly risky issue, and that only people with high security clearance could access them.
"Going to sea in any way was seen as first and foremost a political issue, not an economic issue, because individuals were so controlled," she said.
What's changed now is the fact that North Korea doesn't have the "capacity" to control its borders as tightly as before due to other, more pressing concerns — such as the country's nuclear development and continuous, crippling international sanctions, Smith said.
She said: "They've only got the capacity to focus on certain aspects of state activity at a time now. They're focusing on the nuclear issue, and they don't have the capacity to focus on every aspect of economic activity, and they don't have the money to feed people, so they have to let people do their own thing."
She previously told BI it was "a lot easier" to bypass the country's security apparatus now than it 20 years ago, because some security officials are willing to turn a blind eye in exchange for profits if someone comes back with a catch.
The sheer number of the boats appearing in recent years also suggests that people were leaving North Korea as part of small enterprises rather than a monolithic state enterprise, another expert observed.
It points to an opening of the North Korean economy, said Benjamin Katzeff Silberstein, an editor at North Korean Economy Watch.
He told BI: "It may tell us something about the extent to which economic activity has been liberalised, but also put under pressure.
"In other words, companies run with relative freedom by individuals may have increased space to operate, but in some cases, they may also receive quotas to fill by the state or other government entities.
"In the case of the ghost ships, while their circumstances aren't fully known, the pressure to meet quotas could explain why they need to venture further out into the ocean searching for their catch, perhaps not with adequate fuel resources on board."
Smith added: "It looks like state priorities over vessels have either broken down or been allowed to lapse in order to permit people to go out and find ways to engage in trade to make a bit of money, which is a change.
"It might not be a major change, but it is a change in the way that the government approaches economic activity. It's less security-focused."