The North Korean vessel Chong Chon Gang is partially seen at Manzanillo Harbor in Panama on July 16, 2013. The vessel was stopped and found to have suspected missile material on board. (Rodrigo Arangua/AFP/Getty Images)

Singapore sent a stern warning Monday to companies doing business for North Korea, with a court handing down guilty verdicts to a local shipping agent accused of transferring money to help Pyongyang buy weapons.

The case against Chinpo Shipping — which had transferred millions of dollars for North Korea — revealed a trove of information about how the country has been using intermediaries to send money through the international banking system without detection.

“This is a significant case in terms of prosecuting North Korean middlemen,” said Andrea Berger, a nonproliferation expert at the Royal United Services Institute in London, noting that this was the first case under a Singaporean regulation that bars companies from helping North Korea with its nuclear and missile programs.

“Now there is a possibility of using this case as a precedent for taking action against other middlemen in Singapore, and also potentially abroad, that provide assistance for North Korea’s weapons sales overseas or North Korea’s proliferation activities generally,” she said.

The United States has been trying to cut off Pyongyang’s access to the international banking system as a way to stop it from financing its nuclear weapons program, and this is exactly the kind of action it wants other countries to be taking against North Korean entities.

The case revolved around Chinpo, a small, family-run Singaporean company that had been working with North Korean shipping and trading entities since 1972.

Over the years, the Tan family, the owner, appears to have developed a cozy relationship with North Korea, even allowing the North Korean Embassy to operate out of its modest office in Singapore. The Washington Post recently visited that office, in a shabby tower, and found that both Chinpo and the North Koreans had gone.

Chinpo had particularly close dealings with Ocean Maritime Management, a North Korean shipping company that was sanctioned by the U.S. Treasury Department in July 2014 over a case that sounds like something out of a John le Carré novel: In 2013, an OMM ship was caught going through the Panama Canal. On board, underneath 10,000 tons of sugar, were two disassembled MiG aircraft and 15 MiG engines, surface-to-air missile components, anti-tank rockets and other weapons.

“This constituted the largest amount of arms and related materiel interdicted to or from [North Korea] since the adoption of Resolution 1718,” Judge Jasvender Kaur said in her summation of the case against Chinpo, referring to the U.N. sanctions against North Korea after its first nuclear test in 2006.

It transpired that Chinpo had sent $72,016.76 to a shipping agent operating at the Panama Canal to ensure the passage of the ship, the Chong Chon Gang, on its route from Cuba to North Korea. That was just one of 605 transactions totaling $40 million that Chinpo carried out for North Korea between 2009 and 2013, when the Chong Chon Gang was caught.

“Chinpo believed that OMM was unable to get a bank account and make remittances because OMM was a [North Korean] entity, and so Chinpo readily agreed to make transfers for them,” the prosecutors said in their opening statement submitted to the court.

Singaporean prosecutors charged Chinpo with breaching U.N. sanctions by transferring money connected with North Korea’s nuclear-related program. The U.N. sanctions, designed to make Pyongyang abandon its nuclear ambitions, prohibit trade in large conventional weapons such as combat aircraft, the proceeds of which are thought to be channeled into the nuclear program. Prosecutors also brought a technical charge of remitting money without a license.

In finding Chinpo — run by 83-year-old Tan Cheng Hoe and his two daughters — guilty, Kaur described how they had transferred money with no scrutiny through the company’s bank accounts and taken steps to obscure the source of the funds.

“Since the second half of 2010, Chinpo stopped indicating the name of vessels in the outgoing remittance forms,” the judge wrote in her summation. “According to the statement of Tan Cheng Hoe, more questions were asked by the bank in the U.S. when the vessel name was included.”

Furthermore, Chinpo essentially let OMM use its bank accounts for holding and transferring money, even as the number of ships for which Chinpo was providing services fell to four in 2013. “The reason behind the odd arrangement was obviously to assist [North Korean] entities as they did not have access to the banking system due to U.N. and U.S. sanctions,” the judge wrote.

Speaking after the court verdict, defense attorney Edmond Pereira said it was “very disappointing, very anti-climactic.”

Sentencing will not take place until the end of January. Because the company was charged, and not Tan or his daughters, the maximum penalty is $71,000 for each of the two charges, with no prison sentence.

Fifield reported from Tokyo and Singapore. Miller contributed from Singapore.

Read more:

Hours before first concert in China, North Korean girl band abruptly goes home

North Korea hints it has a hydrogen bomb, but skepticism abounds

North Korea building new tunnel at nuclear test site, satellites show