Panama on Tuesday called for UN inspections of missile parts found aboard a North Korea-flagged vessel as it approached the Panama Canal, weapons Cuba later claimed as its own, AFP reports.
The shipment could constitute a violation of strict UN arms sanctions imposed on North Korea over its nuclear program and further sour relations between the United States and Cuba.
President Ricardo Martinelli tweeted a photo of the contraband haul, which experts have identified as an aging Soviet-built radar control system for surface-to-air missiles.
His government said the contraband munitions were hidden under thousands of bags of sugar aboard the North Korean-flagged Chong Chon Gang, which was stopped on suspicion it could be transporting drugs.
Cuba later claimed the shipment as its own, saying the "obsolete" weaponry included anti-aircraft missile arrays, nine disassembled missiles and other weapons parts, all being sent to North Korea to be repaired and returned to the communist-ruled island.
"The agreements subscribed by Cuba in this field are supported by the need to maintain our defensive capacity in order to preserve national sovereignty," the government said in an English-language statement.
"Cuba reiterates its firm and unwavering commitment with peace, disarmament, including nuclear disarmament, and respect for International Law."
Panama's Security Minister Jose Raul Mulino told RPC radio that the affair now is a matter for UN investigators.
"The Security Council will have to send experts," he said.
The United States meanwhile hailed the Panamanian action.
"We stand ready to cooperate with Panama should they request our assistance," State Department spokesman Patrick Ventrell said, reiterating that any shipments or "arms or related material" would violate several Security Council resolutions.
The magazine IHS Jane's Defence Weekly said Tuesday that the photo tweeted by Martinelli appeared to show an "RSN-75 'Fan Song' fire-control radar system."
The weapons were developed in 1957 and frequently used during the Vietnam War.
Cuba said the shipment contained 240 metric tonnes of weaponry "manufactured in the mid-twentieth century."
But Panamanian officials said the crew resisted, and that the ship's captain attempted to commit suicide after the vessel was stopped.
"The manner in which the cargo was concealed, and the reported reaction of the crew, strongly suggests this was a covert shipment of equipment," Jane's Defence Weekly said in a statement.
Martinelli said the ship, which was sailing from Cuba with a crew of about three dozen, was targeted Friday by drug enforcement officials as it approached the canal and was taken into port in Manzanillo.
After a search, officials found the contraband missiles hidden in a shipment of 220,000 pounds (100,000 kilograms) of sugar.
A Panama government spokesman said an examination of the ship by weapons specialists may take as long as a week.
"The world needs to sit up and take note: you cannot go around shipping undeclared weapons of war through the Panama Canal," Martinelli told Radio Panama listeners on Monday.
The vessel was being held in a restricted zone, and the crew has been detained, officials said. So far, no drugs have been found on board.
Cuba is the only one-party Communist regime in the Americas, and a rare ally of similarly isolated Pyongyang.
North Korea's army chief of staff General Kyok Sik Kim visited Cuba last month and said the two countries were "in the same trench."
North Korea defiantly carried out its third nuclear weapons test in February, triggering even tighter UN sanctions.
Experts say it is unclear whether the North has the technology to build a nuclear warhead for a missile.
UN sanctions bar the transport of all weapons to or from North Korea apart from the import of small arms. Several of the country's ships have been searched in recent years.
In July 2009, a North Korean ship heading to Myanmar, the Kang Nam 1, was followed by the US Navy due to suspicions it was carrying weapons. It turned around and headed back home.
Pyongyang has yet to comment on the latest incident.
Five percent of the world's commerce travels through the century-old Panama Canal, and that is expected to increase following the completion of a major expansion project.