When the coronavirus first appeared, North Korea closed its borders faster than almost any other country.
The secretive nation's weak health care system would face major problems dealing with a large disease outbreak.
But nearly two years later, North Korea still appears to have few tools – other than lockdowns – to fight the coronavirus pandemic.
North Korea has refused offers of COVID-19 vaccines from other countries. It has also rejected the United Nations-supported COVAX vaccine supply program. The World Health Organization says North Korea is one of only two countries that has not yet started vaccination campaigns. The other is Eritrea.
Instead, North Korea has continued border closures and enforced severe travel restrictions within the country.
Some observers question North Korea's claims that it has completely kept the coronavirus out of the country. But experts do admit that the early lockdown orders likely prevented pandemic deaths.
"It works, let's face it. North Korea is able to seal its borders very tightly and control movement. And we know these viruses cannot infect others when they can't move," says Kee Park. He is a North Korea expert at the Massachusetts-based Harvard Medical School.
But as North Korea enters year three of its lockdown, signs of economic problems are developing.
Basic food supplies are now too costly for poorer people in the country. Outside humanitarian aid, an important part of North Korea's economy, has been reduced.
The economy has taken a major hit, says Lee Sang Yong. He is chief editor of the Daily NK, a publication based in Seoul, South Korea.
"Ordinary people now eat only two meals per day instead of three. And the ratio of rice to corn they consume is 3 to 7 instead of 7 to 3. It's clear the economic situation is getting worse," Lee said.
Many experts say the situation cannot continue for much longer.
"We are not sure how long they can continue and endure these kinds of difficulties," said Park Won Gon, a professor at Seoul's Ewha University. He added, "Many people, especially so-called experts on the North Korean economy, are saying next year, probably in the first half...will be the deadline."
There are signs that North Korea is trying to open its border to trade with China, its main economic partner. Satellite photos show North Korea is building several centers to improve safety measures in its import operations.
Kee Park says any wider opening with China may be tricky, since both countries are using a "zero COVID" approach.
North Korea has expressed worry about the effectiveness and side effects of the AstraZeneca vaccine that COVAX has provided. It is also concerned about foreign aid workers who would be necessary to carry out a vaccine campaign.
North Korea could attempt to get COVID-19 treatment pills instead of vaccines. Some observers say the pills could be especially useful in countries that do not have enough vaccines.
But in a pandemic likely seen as a threat to the rule of Kim Jong Un, the leader may instead feel the need to show more control. And that means the lockdown may continue.
I'm Jonathan Evans.