The Trump administration says international trade sanctions are undermining the North Korean economy and that the financial squeeze has compelled Kim Jong Un to negotiate.

“There’s no question these sanctions are working, and that’s what brought them to the table,” Treasury Secretary Steven Mnuchin said.

But information about the North Korean economy is scarce at best — it has never published reliable economic figures. And amid the statistical blackout, some informal indicators indicate that the country has remained stable, according to specialists working from public sources including commercial satellite photography and reports, gathered at great risk, from people within North Korea.

The value of the North Korean won has been steady, according to those reports. So, too, the prices for basics like rice and corn. The price of gasoline spiked in the fall, but it has been falling in recent months. New construction projects continued to pop up, as least through January, according to satellite photography; the lights at night in Pyongyang and the border with China, appeared relatively brighter, though the country as a whole was growing less so.

“There’s certainly a lot of anecdotal evidence that growth is, if not positive, at least flat,” said Daniel Ahn, who in February left his post leading the Office of the Chief Economist at the U.S. State Department, where he studied the economic effects of sanctions.

As Trump and Kim prepare to meet, the status of the North Korean economy is considered critical because it could determine the extent of U.S. economic leverage and whether Kim Jong Un comes to the negotiations as a leader humbled by sanctions or one unfazed by  international financial pressure.

Few doubt that the sanctions have shrunk North Korea’s trade with the rest of the world, particularly over the last nine months. What remains unclear, though, is how much that reduction has constrained the country’s economy.

North Korean officials have offered conflicting views of the sanctions they have faced over the years – calling the trade restrictions both ineffective and “vicious.”

“It is a foolish dream to hope that the sanctions could work on the DPRK,” according to North Korean state media. “The sanctions have failed to stop it from becoming a full-fledged nuclear weapons state and making rapid progress in the building of an economic power.”

The Trump administration, however, has made clear their assumption that the sanctions have been effective. Trump has said the sanctions are “very biting” and Treasury Secretary Steven Mnuchin has cited their “very big impact” on the North Korean economy.

The sanctions appear to have achieved a huge cut in North Korea’s exports – its sales to the rest of the world, mainly China. Exports from North Korea have plunged from about $240 million a month in 2016 to less than $50 million a month by the end of last year, according to IHS Markit Global Trade Atlas. Anecdotal accounts from traders in Chinese cities bordering North Korea back up those figures, too. They say that North Korean factories are closing for lack of Chinese customers.

“I do believe  a major reason why they’re having this meeting is because  the economic sanctions have a very big impact on both their economy and their ability to get pieces of material and other things they need for their weapons program,” Mnuchin said.

What those  trade losses have meant for the overall North Korean economy is unclear, however, because while economists expect to see a downturn, they have seen few signs of it.

“The sanctions have to be creating havoc for the regime,” said William B.  Brown, an economist who grew up in South Korea and who has worked in the analytical arm of the CIA, the State Department, the US Embassy in Seoul, and the National Intelligence Council. “All those coal and textile workers who were producing for export – what are they doing now?”

Brown, who now teaches Chinese and Korean economics at the Georgetown School of Foreign Service, said that he’s been expecting that the North Korean economy – what little we know of it – would begin reflecting that havoc.

“But,” he said, “we’re not seeing it yet.”

To understand an economy, economists often bring to bear huge data sets. But when it comes North Korea, they must rely on tiny shreds of information.

It is a measure of the scarcity of information that one of the most widely used economic indicators from North Korea are the price estimates produced on a shoestring budget by the Daily NK, a website run out of an office in Seoul.

Roughly once or so a month , reporters at the Daily NK confer via cellphone with a network of sources in three North Korean cities. The reporters, some of them defectors, poll their sources back home on a handful of very basic questions.

What is the price of rice? Of corn? Of gasoline? What is the exchange rate?

It is painstaking work requiring some discretion: The informants risk imprisonment.  Sometimes the sources send photographs depicting prices; most times, the price is reported verbally. Each figure is checked against at least two other independent sources in that city, a spokesman said. The data is consistent with another similar survey conducted by Asia Press International, a consortium of journalists.

“We maintain contact with sources inside the country in order to help their voices reach the outside world,” said Daily NK’s editor-in-chief Lee Sang Yong. “Of course this work is dangerous, but our sources are well aware of the dangers, as are we. Our core goals and values are not deterred by the inherent dangers of this work, and we are able to mitigate the risks involved by adhering to strict security protocols.”

For experts outside of North Korea, their price information – as basic as it is – is considered precious.

Marcus Noland, an economist at the Peterson Institute and author of a book and several studies about North Korea, said that while no economic indicator alone is perfect for measuring the impact of sanctions, the first he looks at is the exchange rate for the North Korean won.

And for that, he turns to the Daily NK. And despite the sanctions, the exchange rate for the North Korean won has remained stable for more than three years – about 8,000 won per dollar – a remarkable equilibrium given the growing trade deficit.

“The single greatest mystery in the North Korean economy is the stability of the won,” Noland said.

It is a mystery because,  among other things, the kind of trade deficit that North Korea is running – it is importing much more than it is exporting – normally would depress the value of the won. So what’s keeping the value up?

Economists propose a number of possibilities. It could be that the government is propping up the won by buying them up using reserves of foreign currency. Or the regime could be expanding its illicit businesses – cybercrime, selling arms, counterfeiting cigarettes and currency – in order to compensate for the trade deficit. Or it could be that the growing tolerance for markets and private investment in North Korea is  providing the kind of upward boost necessary to keep the economy aloft.

“We just don’t know,” Noland said. “It might also just be a matter of time.”

Other prices detailed in the Daily NK survey also reflect stability – particularly the prices of staples like rice and corn.  

One item that has fluctuated in price – wildly – is gasoline. It spiked in the fall, more than tripling in price to 24,000 won per kilogram.

That fluctuation was quickly seen as evidence that the sanctions, which limit sales of refined petroleum products to North Korea, were having an effect. But in recent months, that price, too, has fallen back, though not all the way, to about 12,000 won per kilogram.

As a result, analysts who have been waiting years for clear signs that the sanctions have harmed the North Korean economy are still mostly waiting.

The U.N. began imposing sanctions in 2006 and for years, as more and more sanctions have been issued, U.S. officials have said they were effective. Many assumed that the North Korean economy, which had undergone devastating famines in the ’90s, was fragile. As far back as 2009, UN ambassador Susan Rice said the latest round of sanctions at the time was “unprecedented” and that they will have “teeth that will bite.”

That strong rhetoric continued. But over the years, the North Korean economy and its weapons programs appears to have been undeterred – they are now producing better rockets, have conducted more nuclear tests, and have had a reportedly growing economy.

The central bank of South Korea, which publishes an annual estimate of the size of the North Korean economy based on scraps of public data as well as national intelligence, said that the North Korean economy grew 4 percent in 2016 – more than either the U.S. or South Korea economies. Through 2016, it had grown four of the last five years. Its estimate for 2017 is expected in July.

“While estimates vary widely, the South Korean central bank says the North Korean economy has grown… I too think the direction is likely positive,” said Ahn, who is currently a professorial lecturer at Johns Hopkins SAIS.

Some satellite photography leads to similar conclusions.

Curtis Melvin, a researcher at the US-Korea Institute at Johns Hopkins SAIS, spends much of his days analyzing satellite photographs of North Korea, looking for new construction or other signs of economic activity, such as smoke from a  factory. He said the pace of major building projects tapered last year, but that big projects are still going up, including a coastal tourist resort, and that the economy does not appear to be shrinking.

“I look at satellite imagery every day. I have the largest non-governmental database of North Korean factories,”said Melvin, noting that his review only runs up through June of 2017. “And from the satellite imagery, I cannot point to anything that says this factory was closed since the sanctions have been adopted.”

Ahn’s analysis of nighttime images of North Korea, by contrast,  offers mixed results. Ahn has conducted an analysis of satellite photography at night, comparing the brightness of North Korean cities over time. The measurement of brightness can be difficult because of cloud cover and the reflection of moonlight from the Earth’s surface, but economists often use it as a measure of economic activity.

Ahn said the results suggest that the country as a whole has dimmed over time, though some key areas, such as Pyongyang and the border with China, have brightened relatively speaking.

“At a broad level the images of North Korea are getting darker, but parts are getting brighter,” Ahn said. One explanation, Ahn said, is that “the regime is shifting what limited resources it has toward its own elites in those areas to ensure it remains in power.”

It could be, several observers noted, merely a matter of timing. Despite years of strong rhetoric from the U.N. and U.S. officials, it wasn’t until March of 2016 that the sanctions began to target, in a general way, the North Korean economy, analysts said. Until that point, the U.N. sanctions against North Korea were largely “targeted” – that is, they were aimed at specific individuals, firms or military items directly related to the regime.

Then, in March 2016, the U.N. issued sanctions limiting exports of North Korean coal, a key element of foreign trade, a measure that took broad aim at the North Korean economy. Follow up sanctions went further in that direction – limiting other key exports, such as textiles and seafood.

Last year, the trade statistics began to reflect the decline, particularly after China appeared to more rigidly enforce the sanctions. North Korean exports dropped steeply. (The trade figures are about the only detailed economic figures we have from North Korea, and they are available because North Korea’s trade partners make them available, not North Korea.)

Anecdotally, at least, that drop has created hardship.

“Multiple sources have told us that a common phrase circulating throughout the country is: ‘Those who were eating three meals a day are down to two, and those previously eating two meals have only one,'” the Daily NK representatives said by email.

It is reports like that, as well as last year’s decline in North Korean exports, that has renewed hopes that the sanctions are working and putting pressure on Kim.

“Maybe Kim, now reaching out to Seoul and Washington, is all the evidence we need,” Brown said.