NEW YORK — It started with a tip: A rusty North Korean freighter, which had not plied the Caribbean in years, was carrying drugs or arms amid tens of thousands of sacks of Cuban brown sugar.
It ended with a five-day, eventually violent standoff between Panamanian marines and 35 North Korean crew members, armed largely with sticks, who were subdued and arrested while their captain, saying he was suffering a heart attack, tried to kill himself.
Underneath all that sugar were parts for what appeared to be elements of an antiquated Soviet-era missile radar system that was headed, evidently, to North Korea — a country that usually exports missile technology around the world, rather than bringing it in.
On Tuesday, US and Panamanian officials were still trying to solve the mystery of the vessel, the Chong Chon Gang, and to understand why its crew had fought so hard to repel a boarding party as it attempted to traverse the Panama Canal.
After all, the equipment they were protecting, and which US officials speculated was headed to North Korea for an upgrade, would make a nice exhibit in a museum of Cold War military artifacts.
“We’re talking old,” one official briefed said. “When this stuff was new, Castro was plotting revolutions.”
But the episode also offered a window on the desperate measures North Korea is taking to keep hard currency and goods flowing, at a time when its ships are tracked everywhere, old customers like Syria and Iran are facing sanctions and scrutiny, and its partners have dwindled to a few outliers.
The role of Cuba is a particular element of the mystery — at a time when Washington has talked of relaxing restrictions and Cuba’s leadership has seemed more eager to improve its ties with the West than to strengthen relations with Cold War-era partners.
Even by the measure of bizarre stories about North Korea’s black market dealings, the events of the past five days in Panama set some records.
In recent times North Korean shipments to Myanmar and the Middle East have been tracked and in some cases intercepted, a testament to how closely US spy satellites follow the country’s aging cargo fleet.
But rarely have North Korean sailors tried so intently to stop a boarding and inspection, in this case cutting the cables to cranes that move cargo, in an apparent effort to keep the cargo buried under sugar.
Officials were wondering whether the sugar was a barter payment for work on the radar system.
“What I can say for sure is that, looking at illicit North Korea trade, their ships in particular, these guys are stumped for money; they are incredibly poor,” said Hugh Griffiths, an arms trafficking specialist at the Stockholm International Peace Research Institute. “Business deals that might look silly to us don’t look ridiculous to them.”
Panama’s president, Ricardo Martinelli, who visited the vessel after the crew had been subdued, announced the discovery in a radio broadcast Monday, making it clear that the North Korean ship was in blatant violation of numerous UN sanctions.
He even posted a photograph of the contraband on his Twitter account.
Based on that photo, IHS Jane’s Intelligence, a defense consultancy, identified it as an SNR-75 “Fan Song” fire control radar for the SA-2 family of surface-to-air missiles.
The component is important for guiding a missile to its target; the Soviets began building similar systems in the mid-’50s, well ahead of the Cuban missile crisis.
“One possibility is that Cuba could be sending the system to North Korea for an upgrade,” IHS Jane’s said in a statement. “In this case, it would likely be returned to Cuba and the cargo of sugar could be a payment for the services.”
But IHS Jane’s added that the radar equipment could also have been en route to North Korea to augment North Korea’s air defense network, which it said was based on obsolete weapons, missiles, and radars.
That raised the possibility that other elements of the shipment were aboard, or on other ships.
“We’re going to keep unloading the ship and figure out exactly what was inside,” Martinelli said. “You cannot go around shipping undeclared weapons of war through the Panama Canal.”
There was no comment Tuesday from North Korea or Cuba on the seizure of the vessel.