A customs specialist who works for Panama's public security ministry said that, even assuming that is true, North Korea and Cuba appear to have breached Panamanian law.
"There is a process [in Panamanian law] for declaring what goods are onboard," former senior U.S. Customs official Steve Atkiss said. "They didn't do that."
Mr. Atkiss, who now works for the Washington-based Command Consulting Group, said it might take as long as a week to complete the search of the Chong Chon Gang.
As soon as the ship was boarded last week, the North Korean crew had "sabotaged the cable and crane system" that the freighter was equipped with for loading and unloading, Mr. Atkiss said. As a result, the 10,000 tons of sugar the vessel was carrying was being unloaded by hand one sack at a time.
In a statement issued late Tuesday, Cubaan Foreign Ministry came clean on what it said are 240 metric tons of military equipment on the freighter, including two air-defense missile systems with nine missiles "in parts and spares," plus two MiG-21 fighter jets and 15 engines for them.
The statement said the cargo is "obsolete defensive weapons ... all of it manufactured in the mid-twentieth century — to be repaired and returned to Cuba."
The two missile systems — Volga and Pechora — are 1960s- and '70s-era hardware. One such system shot down the American U-2 spy plane piloted by Francis Gary Powers in 1960, according to an Air Force website. They are considered largely ineffective against advanced stealth bombers, such as the B-2.
In 2007, Russia unveiled an upgrade to the Pechora system, which counts North Korea among the former Soviet satellite states that have deployed it. The upgrade can work with older missiles, according to a report from the RIA Novosti state news agency.
IHS Jane's military analyst Neil Ashdown said the missile guidance systems might be going to Pyongyang for upgrade, rather than repair, and that in either case "the sugar is likely to be payment."
Tuesday's statement from Havana said Cuba has a "need to maintain our defensive capacity in order to preserve national sovereignty," adding: "The Republic of Cuba reiterates its firm and unwavering ... respect for international law."
Nonetheless, it seems to many observers that Havana has been caught in a flagrant effort to avoid U.N. Security Council sanctions on North Korea that have been imposed repeatedly over the past few years in response to Pyongyang's determination to press ahead with nuclear and ballistic-missile programs.
"I would submit that if the Cuban government believed what they were doing was on the up and up ... they would have declared the true contents of their cargo," Mr. Atkiss said.
U.N. Security Council Resolution 1718 reads, in part: "All member states shall prevent the direct or indirect supply, sale or transfer [to North Korea of any] combat aircraft ... missiles or missile systems."
On Monday, State Department officials told reporters that member states like Panama could report alleged breaches of the sanctions to a special U.N. committee.
Asked about this, Mr. Atkiss said that Panamanian officials would be guided "by the advice they get from the international community about what they find and to what degree the Cuban and North Korean government might have been in breach of U.N. sanctions."
Gen. Kim Kyok-sik, chief of general staff for North Korea's armed forces, visited Cuba two weeks ago for meetings with President Raul Castro and others, Cuba's official media reported at the time.