They come and they go without much international fanfare: delegations of North Korean ministers in Mongolia, invited by the pro-Western government to discuss trade, cultural ties and questions of "mutual interest."
The specifics of these meetings are hard to nail down. "The two sides exchanged views on the issue of further developing the exchange and cooperation between security organs of the two countries and matters of mutual concern," one news release stated in November.
But unrevealing as these news releases may be, they hide a more interesting relationship: Mongolia, a fast-growing democracy whose mineral riches have made it the darling of global capitalism, has cultivated perhaps the warmest relationship of any country with the notorious Hermit Kingdom.
Intelligence and diplomatic officials see the Mongolian connection as a source of information on the North's activities, as well as a potential conduit for dialogue with the unpredictable regime in Pyongyang.
With the North again rattling swords — a long-range rocket now stands ready for launch — opportunities to sound out senior officials are rare.
At the moment, for instance, North Korea watchers are reading tea leafs, trying to figure out whether longtime defense minister, Marshal Kim Jong Gak, has been replaced by Gen. Kim Kyok Sik, who is reputed to have closer ties to the ruling Kim Jong Un.
"This is exactly the kind of stuff that drives us crazy," a Western diplomat in Seoul said, requesting anonymity. Kim Kyok Sik "commanded the units that launched the unprovoked artillery attack on the South that killed a bunch of people in 2010."
And this is exactly where Mongolia comes in handy. "Working through China is very difficult," the diplomat said. "But the Mongolians might be able to just make a phone call."
Sandwiched as it is between giants China and Russia, Mongolia is expert at navigating the rocky diplomatic territory between friendly disagreement and impudence.
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It shouldn't come as a surprise then that it has proven adept at balancing ties with Washington and other Western powers while pursuing warm relations with North Korea, Iran and other pariahs.
The Mongolian press regularly refers to the United States as "our third neighbor." Mongolian President Tsakhia Elbegdorj met President Barack Obama at the White House in 2011, and President George W. Bush dropped in on Elbegdorj's predecessor in 2005 — in part to thank Mongolia for sending troops to join US-led forces in Iraq and Afghanistan.
Even as foreign direct investment from G7, Russian and Asian investors has surged in Mongolia, earlier this year Elbegdorj became the first foreign leader allowed to visit the Iranian centrifuge array at the uranium enrichment center in Natanz.
Mongolia also has strong ties with two energy-rich Central Asian states known for their standoffish attitude, Uzbekistan and Turkmenistan. And it has kept strong ties with China, its largest trading partner, in spite of open criticism in Mongolia's press about the suppression of their ethnic cousins in China's province of Inner Mongolia.
But it is the relationship with Pyongyang that stands out most starkly. During the Korean War, when Mongolia was effectively a communist satellite caught between China and Russia, Mongolia sent 200,000 head of cattle to help feed the North's population.
The tacit alliance ended in 1990, when Mongolia recognized South Korea and embraced market reforms and democracy. But after some rocky times later that decade, ties have flourished again.
A top-level North Korean military delegation's visit to the Mongolian capital was revealed in 2009, partly by accident — literally, an automobile accident. The crash made the local papers since North Korea's deputy defense minister required treatment at an Ulan Bator hospital.
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So what exactly is discussed when the North and Mongolia meet? North Korea may press Mongolia to follow China's example and turn over North Korean defectors who use Ulan Bator's air links as a gateway to South Korea. To date, the Mongolian government has held its ground, winning praise from human rights groups.
But land-locked Mongolia also has serious economic interests in developing the so-called Rahon Special Economic Zone, a port development at the northern tip of North Korea that offers Mongolia a way to export manufactured goods via the trans-Siberian railroad, bypassing Chinese and Russian ports.
There is also a controversial labor arrangement whereby some 5,000 North Koreans work in Mongolia's booming mines and factories. Many work under miserable conditions, according to The Independent, and are likely forced to turn their pay over to Pyongyang — in effect, allowing North Korea to raise hard currency otherwise banned under sanctions.
The fact that neither the US, South Korea nor Japan has made an issue of these workers suggests there are good reasons not to upset Mongolia's ties with the North.
But don't oversell the Mongolia-North Korea friendship, experts say.
"These [North Korean] ties are based neither on common interests nor shared values but exclusively on the psychological imperative to defend maximum sovereignty and maintain room for maneuver," wrote Munkh-Ochir Dorjjugder, director of Mongolia's Institute for Defense Studies, in a paper for the Brookings Institution."The last thing the Mongolian government is willing to do is to act, once again, as the 'mouthpiece' and 'promoter of ideology' of any neighbor, real-world or virtual."