Haitian police announced in April 2024 that they had seized the two boxes. They contained 12 assault rifles, 14 pistols and 999 ammunition cartridges.
A police photo clearly shows weapons from two different US-based manufacturers.
The shipment had travelled nearly 1,200km (746 miles) from Fort Lauderdale in Florida to Cap-Haitien in northern Haiti, on the Rainer D cargo ship.
It is not clear where the guns had been bought. Guns are not manufactured in Haiti, and previous seizures have included guns bought in Florida.
Sometimes dubbed the "gunshine state", Florida was one of about 30 states where, until 2024, private, unlicensed sellers could sell firearms, for example at gun shows and online, without doing background checks. As president, Joe Biden tightened these rules nationally.
The UN panel says two Haitian brothers based in the US had used "straw buyers" – individuals buying on their behalf – to buy the weapons in the seized shipment.
Experts say this is a common method, often with the guns transported in multiple shipments of small quantities, a process named "ant trafficking".
Around the time the weapons were packed into the shipping container, a wave of gang violence swept through the Haitian capital, Port-au-Prince.
Gangs freed thousands of inmates from the main prison, and blockaded the capital's ports and airport.
In March 2024, Prime Minister Ariel Henry, unable to return from an overseas trip, agreed to step down.
A record 5,601 people were killed in gang violence in Haiti in 2024, according to the UN. Its agencies say nearly a tenth of the population – over a million people - have fled their homes and half the population faces acute hunger. Kidnapping and extortion are rife.