North Korea and Cuba yesterday signed a trade agreement that will see them exchanging goods via a barter system, according to a report from Prensa-Latina.

The deal was one of two new protocols signed in Cuba’s Ministry of Foreign Trade and Foreign Investment, with the other focusing on scientific and technical development.

“The trade protocol establishes the transaction of goods through the barter mode of exchange, first for supplies for the Cuban Railway Union and to promote the island’s sugar industry,” the article reads.

While some experts have suspected North Korea of bartering for illicit goods with Cuba in the past, the official announcement of such an agreement is relatively rare.

According to the NK News KCNA Watch data tool, the only other mention of a barter deal with another country in North Korea was a 2002 protocol with Vietnam. One further article mentions bartering with South Korea as part of a larger trade relationship in 1997.

“In the case of Cuban-North Korean barter, the tradeable goods will still likely be valued in U.S. dollars, however, neither party will have to martial their hard currency reserves or transact through the international financial system to conduct international trade,” Curtis Melvin, a researcher at the U.S. Korea Institute in Washington, D.C. told NK News.

“This frees up scarce foreign exchange for other uses – such as trading with other partners for whom barter transactions are not possible or desirable.”

The news report did not provide further details on what goods North Korea could provide to help Cuba’s rail union, though DPRK leader Kim Jong Un has recently expressed an interest in revamping the North’s creaking rail infrastructure.

The specific mention of sugar in the news report could also raise eyebrows. In 2013, a North Korean vessel was infamously caught smuggling weaponry and military systems through the Panama Canal. The equipment was hidden under 10,000 tons of sugar.