How does a country as seemingly poor as North Korea (DPRK) finance its costly nuclear weapons program? Apparently by illegally smuggling arms to countries such as Iran, Pakistan, and Afghanistan. Despite a UN ban on arms sales from the country back in 2006, it’s believed the DPRK earns $1 billion per year through the practice.

As we’re reminded today, the illegal arms trade continues largely unabated. A plane, registered in Georgia (the country, not the state), was searched and then seized in Thailand after authorities found on board, “rocket-propelled grenades, missile and rocket launchers, missile tubes, surface-to-air missile launchers, spare parts and other heavy weapons.”

The plane’s manifest claimed that its cargo consisted of oil-drilling equipment. Obviously that was a lie.

Authorities in Bangkok said today it was unclear where the plane carrying the 35-tonnes of arms, an Ilyushin IL-76 registered in Georgia, was heading. But suspicion immediately fell on Iran, the destination of a previous illegal weapons shipment impounded in the United Arab Emirates in July. Panitan Wattanayagorn, a Thai government spokesman, said the plane had initially planned to refuel in Sri Lanka. For unknown reasons, the crew asked to make an emergency landing in Bangkok on Friday. Sri Lanka denied any knowledge of the arms shipment. There was also speculation in Bangkok that it was destined for Pakistan or Afghanistan.

Five crewmen were detained, including four from Kazakhstan and one from Belarus. Both Kazakhstan and Belarus have close relations with Russia, which has close relations with North Korea.

As the Guardian notes, this is just the latest seizure of illegal arms from the DPRK.

The Bangkok arms seizure followed several similar recent incidents. In July, the French-owned, Bahamian-flagged ANL Australia bound for Iran was intercepted in the UAE after a US tip-off. The ship was found to be carrying containers of small arms made in North Korea, military hardware and sufficient explosive powder to arm thousands of short-range rockets. Also uncovered was a cache of 2,030 detonators for 122mm rockets and other rocket components. The manifest also detailed the cargo as oil drilling supplies. Investigators said the arms shipment had travelled a complicated roundabout route. Ten large containers left the North Korean port of Nampo on 30 May aboard a North Korean vessel, and were transferred three days later to a Chinese ship at the Chinese port of Dalian. They then went on to Shanghai, where they were loaded on to the ANL Australia, turning up in the Gulf two months later.

US officials said the ANL Australia was one of five vessels caught this year carrying large consignments of weapons apparently intended for Iran’s militia clients such as Hezbollah and Hamas, or for the al-Quds brigade of Iran’s Revolutionary Guard that protects Iran’s nuclear facilities and supports insurgents in Iraq. In three cases, the US said the arms included North Korean or Chinese-made weapons.

It’s long been suspected that North Korea and Iran are cooperating on the development of nuclear weapons. It’s already known that the former and Pakistan have cooperated on the issue in the past.