Its action also raises the question of how far United States allies in Asia are prepared to go to enforce a comprehensive United Nations ban on North Korean arms exports. Should the Kang Nam, the North Korean-registered ship at the center of the row, seek to refuel in Singapore or another port, the ban would be put to the test.
Under the UN Security Council resolution, adopted after North Korea's May 25 nuclear test, vessels suspected of breaking the embargo must undergo inspection, either on the high seas or at port. But any inspection depends on the cooperation of a ship's captain. Few believe that the Kang Nam would comply.
UN resolution requires inspection
Within Southeast Asia, the US can count on longstanding military ties with Singapore and Thailand, both of which trade with Burma. An interception by any of their naval forces seems highly unlikely. Singapore has said that it would act "appropriately" if the Kang Nam docks there.
South Korean TV said Tuesday that the ship, which is being tailed by a US Navy destroyer, was 200 nautical miles southeast of Shanghai. Earlier, the Irrawaddy, a news website run by Burmese exiles in Thailand, reported that the ship would dock within days at Thilawa, a deepwater port in Burma. It reportedly sailed from North Korea on June 17.
The UN resolution requires port authorities to check suspicious North Korean cargo ships for contraband. A UN member country could ask Burma to inspect the vessel on arrival. But that raises the question of what constitutes a proper search, says Mr. Pinkston.
North Korea and Burma are pariah states in the eyes of many Western powers. In turn, both countries rely on China for diplomatic and economic support in the face of Western sanctions.
N. Korea eager for foreign currency
The Kang Nam is believed to be carrying conventional small arms. In the past, North Korea has sold artillery and rocket launchers to Burma, says Bertil Lintner, a Thailand-based journalist and author of several books on both countries. In 2007, the same vessel docked in Burma and offloaded some heavy equipment, fueling suspicions of weapon systems transfers.
Its deepening ties with Burma has raised fears that it might sell long-range missiles to the regime, which is also pursuing Russian nuclear technology. Russia has agreed to build a nuclear reactor in Burma and has begun training Burmese technicians in Russia.
But that doesn't mean that Burma is about to follow North Korea into the nuclear club, says Mr. Lintner. "My sense is that Russia doesn't really want Burma to go nuclear. The [training] courses are pretty meaningless if they want to use nuclear energy for military purposes."
Some analysts have speculated that the Kang Nam could be using Burma as a transshipment or refueling stop. Last year, a North Korean cargo plane landed in Mandalay and unsuccessfully sought to cross into Indian airspace to reach Iran. The Wall Street Journal reported that the US government suspected that the plane was carrying missile components.
'Difficult to assess what's on board'
In recent years, though, the US and its allies have often been blindsided by North Korea, making it difficult to track contraband shipments, says Paul Quaglia, director of PSA Asia, a security consultancy in Bangkok. Moreover, he and other analysts are skeptical of Burma's wherewithal to acquire and use sophisticated weapons like long-range ballistic missiles.
The Kang Nam's cargo may not be as illicit as claimed, he suggests. "It's difficult to assess what's on board, and the US track record isn't exactly stellar in this department."
In 2006, North Korean experts on tunneling built underground facilities in Burma's new capital, according to Mr. Lintner, who obtained photos of the tunnels. The capital Naypyidaw is a purpose-built center far from Burma's major cities, including its commercial hub Yangon.
Isolated Burma an ideal customer
In some respects, Burma is an ideal customer for North Korean weapons. It has hard currency and a shared loathing of Western meddling and is stymied by sanctions. Burma's generals also appear to be impressed by North Korea's use of missiles as a deterrent against "regime change," says Sean Turnell, an economics professor at Macquarie University in Sydney.
Burma's currency reserves have risen to around $4.5 billion, thanks to gas exports to Thailand and other resource-industry investments, says Mr. Turnell. Perhaps half of government expenditure goes on the military, affording room for increased spending on weapons, if they are on sale.
"They're certainly interested in getting the gear, but they're been greatly restrained by where they can get it from," he says.