KYIV, April 1 – Ukraine has foiled an attempt by two Iranian nationals to buy parts of an advanced missile in Kyiv earlier this year, the Daily Beast reported citing sources at the intelligence service.

Ukraine’s security service arrested the men in January and found parts of the missile in their vehicle, the newspaper said. What followed became a secret diplomatic incident, and both men were detained and then quietly deported to Iran.

Vasyl Hrytsak, the head of Ukraine’s security service SBU, described this all to American government officials during a recent trip to Washington, the Daily Beast reported.

The attempt as alleged by Ukrainian intelligence sources likely violated United Nations’ prohibitions on Iranian arms procurement. And it shows Iran may intend to procure weapons that would let it make the Persian Gulf more dangerous than ever.

Hrytsak told American officials Iranians tried to procure an X-31 anti-ship missile components, produced in Ukraine. “X-31” can also be rendered as a Kh-31 missile, depending on how you transliterate the cyrillic.

Officers from the Security Service of Ukraine (SBU) arrested the men when they were in possession of parts of the missile as well as technical documents related to its use, according to pictures of the arrest reviewed by The Daily Beast. (Those pictures included images of a vehicle’s open trunk, packed with missile parts.) One of the men, according to Hrytsak, is named Abdi Biyan and was a military attache at Iran’s embassy in Kyiv.

“The diplomats in Ukraine are not there for Chicken Kiev,” said Tom Karako, a fellow at the Center for Strategic and International Studies. “They’re there to get this kind of stuff.”

The Kh-31 is a Russian-designed anti-ship weapon that can fly along the surface of the sea at supersonic speeds.

Iranian acquisition of Kh-31 missiles could improve its ability to attack U.S. and Gulf Arab countries’ naval forces as well as commercial maritime traffic transiting the Strait of Hormuz, the thin strip of sea between Iran and the United Arab Emirates that connects the Persian Gulf to the Arabian Sea.

According to the U.S. government’s Energy Information Administration, 18 million barrels of oil went through the strait every day in 2016—more oil than moved through any other choke point that year. Iran has repeatedly threatened to shut the strait in response to tensions with the U.S. and Europe. Expanded Iranian capabilities to harass ships could have economic consequences as well as military ones.

This alleged attempt wouldn’t be the first time Iranians tried to get weapons from Ukraine. In 2005, Ukrainian prosecutors revealed that Iran smuggled Kh-55 air-launched cruise missiles out the country in 2001—a move U.S. officials reportedly believed was assisted by corrupt senior officials in the government of former President Leonid Kuchma. Missile experts believe that the illicitly acquired Kh-55 missiles formed the basis of Iran’s “Soumar” long-range cruise missile revealed in 2015. (db/ez)