WASHINGTON, April 29 (UPI) -- Amid increasingly rancorous U.S.-Iranian relations over Tehran's nuclear energy program, the U.N. sanctions regime scored a small victory March 29 when Azerbaijan's customs and frontier officials detained a Russian cargo bound for Iran's Bushehr nuclear facility.

Khazar Ibragim, a spokesman for Azerbaijan's Interior Ministry, said the convoy of trucks carrying the shipment, sent from Russia's Atomstroyexport, the contractor building the Bushehr facility, was detained in Astara, on the Azerbaijani-Iranian border, in order to ensure the cargo's content didn't breach U.N. sanctions.

"There are certain U.N. Security Council resolutions against Iran in place, and we want to know whether the cargo complies with the resolutions," he said. "Which is why we requested that the Russian side specify the content of the cargo."

Moscow demanded Azerbaijan explain itself, but as of April 23 Atomstroyexport spokeswoman Irina Iesipova said there had been no progress in resolving the standoff. In siding with the United Nations, Azerbaijan has managed to antagonize both Iran and Russia.

In Moscow, Russian Federation Council Sen. Vladimir Zhidkikh, a member of the council's subcommittee for nuclear power, said that while "the detainment of our cargo already for 25 days can be called a misunderstanding," the load's retention by Azeri customs officials is typical behavior by "low ranking" corrupt officials designed to enrich themselves or gain promotion.