WASHINGTON — Fighter jet parts seized from a North Korean ship by Panamanian authorities were likely intended for use by North Korea, an apparent violation of UN sanctions, an arms control institute says. The findings by the Stockholm International Peace Research Institute contradict Cuba's claim that it was not violating the sanctions as it was sending equipment to North Korea for repairs and expected it to be returned, including MiG aircraft and motors, missiles and anti-aircraft missile systems. UN sanctions forbid North Korea from trading arms to deprive it of technology and revenue for its pursuit of nuclear weapons and ballistic missiles. If the Cuban equipment was intended for North Korean use, it would suggest Pyongyang is struggling to maintain its aging conventional forces. The ship, Chong Chon Gang, was intercepted July 15 in the Panama Canal, with 25 containers of Cuban military equipment found beneath the 10,000 tons of sugar. The equipment was not listed on the ship's manifest. Experts at the Stockholm institute say they have seen a report and photographs compiled by Panamanian authorities and the United Nations Organization on Drugs and Crime on what was found in the containers. The institute's experts said there was other cargo not mentioned by Cuban officials in public statements, including items of ammunition for rocket-propelled grenades and conventional artillery, much of it in mint condition and in the original packing cases. “They clearly were not ‘to be repaired and returned to Cuba,'” the institute says in an analysis. The analysis was published Tuesday by 38 North, the website for the US-Korea Institute at Johns Hopkins School of Advanced International Studies. It was written by Hugh Griffiths, who heads the Stockholm institute's program on countering illicit trafficking, and research intern Roope Siiritola. After the seizure, Cuba said the cargo included “obsolete defensive weapons” including two MiG-21 jet aircraft and 15 motors, nine missiles in parts, and two anti-aircraft systems that they were sending to North Korea “to be repaired and returned.” North Korea also said it had a “legitimate contract” to overhaul “aging weapons” to be sent back to Cuba. UN sanctions state that member states shall prevent the direct or indirect supply, sale or transfer of all arms and materiel to North Korea, and related spare parts, except for small arms and light weapons. The Stockholm institute says the MiG fuselages were packed carelessly, with no padding to protect the extremities from damage at sea, suggesting there were intended to be culled for spare parts. The engines were more securely attached and protected, suggesting they were intended to be used as replacement engines. The institute says North Korea has a track record of attempted illicit or clandestine procurement of the MiG engines and aircraft, including two other reported instances of it since 2009 and another in 1999. The July seizure came less than two weeks after a North Korean military delegation met Cuban leader Raul Castro in Havana on July 2. In mid-August, a UN panel of experts monitoring sanctions against North Korea traveled to Panama to investigate the arms seizure. Their report has yet to be made public. If they find sanctions have been violated they could recommend the Security Council add individuals or entities involved in the transfer to a UN sanctions list. Member states may then follow up by imposing travel and financial restrictions on those added to the list. — AP