But the screw has tightened since North Korea's last nuclear test in 2009. Its weapons exports have been banned under U.N. Security Council resolutions. The sanctions call on member states to inspect and confiscate suspect cargoes, also including certain luxury goods, and report them to the world body.
The United States is also likely to seek tighter restrictions on the North after the latest launch, although it could face opposition from China, the North's only major ally.
Former British ambassador to North Korea, John Everard, who until recently served as coordinator of a U.N. panel of experts that reports on the implementation of the sanctions, said that while the North's arms exports haven't stopped, seizures have already caused it considerable financial and reputational damage, particularly when information about their customers becomes public.
But implementation has been patchy. The North goes to great lengths to circumvent controls, typically using neighboring China and other countries en route as transshipment points.
Tracking secret weapons shipments is difficult, but some trends emerge. Recent seizures indicate that North Korea is still shipping missile technology to Syria.
Last month, U.N. diplomats reported that 445 graphite cylinders from North Korea that can be used to produce ballistic missiles were seized in May from a Chinese freighter ship at the South Korean port of Busan on their way to Syria. In October 2007, propellant blocks that could be used to power Scud missile were seized from a ship heading to Syria, according to a report by the U.N. expert panel, released this June.
Iran and North Korea have shared missile technology, but it's less clear what the current state of their cooperation is, said a senior State Department official, speaking on condition of anonymity to discuss diplomatically sensitive, counter-proliferation issues.
In December 2009, Thailand intercepted a charter jet from Pyongyang carrying 35 tons of conventional weapons including surface-to-air missiles that Thai authorities reported were headed for Iran — apparently for the use of a proxy militant group. The White House recently remarked on how Thailand had interdicted a North Korean weapons shipment bound for Hamas.
The U.S. official said North Korea is seeking buyers for its cheap weapons in Africa. In recent years, there have been seizures of shipments heading to countries including Eritrea, Republic of Congo and Burundi.
But combined with its shrinking markets in the Middle East, Myanmar's promise to end its military trade could badly hit North Korea's pocket book.
Myanmar's former ruling junta entered into commercial contracts with North Korea, most notably after a high-level military delegation visited Pyongyang in late 2008. According to the U.S., one agreement was for North Korea to assist Myanmar in building medium-range, liquid-fueled ballistic missiles.
In recent months, the United States has credited Myanmar with "positive steps" toward severing those military ties as the newly elected civilian government courts better relations and investment from the West.
But the U.S. official said Myanmar is not yet in compliance with U.N. Security Council resolutions, as North Korea still seeks to ship goods to Myanmar to fulfill the contracts.
Pennington reported from Washington.