Unit 190, a secret arm of the Iranian Revolutionary Guard’s Quds Force, is made up of only about 24 people and operates out of a warehouse at Tehran’s main airport.

The leader of the unit is 46-year-old Benham Shahariyari, who runs a network of front companies which skirt sanctions packing RPG’s, night-vision equipment and long-range rockets in powdered milk, cement and spare vehicle parts.

Michael Eisenstadt, director of Military and Security Studies programs for the Washington Institute for Near East Policy, told Fox News: “Very often arms and explosives were placed in trucks underneath legal cargo in order to hide them.”

When Turkey intercepted containers filled with 122mm mortar shells and explosives in 2007vdestined for Hezbollah via Syria in violation of UN Security Council Resolution 1747, the bill of loading had Shahariyari’s signature on it, Fox said.

And the US Treasury had sanctioned front companies used by Unit 190 to transport weapons to Hezbollah, and other terrorist groups in the Middle East in direct violation of UN Security Council resolutions, it is alleged.

On December 21, 2010, the US Treasury designated shipping company Liner Transport Kish to provide material support including weapons to Hezbollah on behalf of the Iran’s Revolutionary Guard Corps. Its manager, Sayyed Jabar Hosseini, is also an employee of Unit 190.

Then in January 2013, the US Navy intercepted 40 tons of anti-tank and anti-aircraft missiles on board a boat named the Jeehan-1 – weapons that western intelligence officials say were destined for the Houthis – the very rebels who just took control of Yemen’s capital, forcing the evacuation of the US Embassy on Wednesday.

Pentagon Press Secretary Rear Admiral John Kirby told reporters on Tuesday: “We know that there is a relationship between the Houthis and Tehran. We’ve been very clear on multiple occasions about our concerns about the tentacles that Iran has throughout the region, specifically with support to groups and organizations that aren’t doing anything to increase stability in the region.”

Explosions that rocked Khartoum in October 2012 were also caused by weapons supplied by Unit 190, Fox said.

Mr Eisenstadt said: “Apparently, that was a compound that was probably used as a transshipment point. The Iranians would bring in arms from Iran to Port Sudan and they would bring the arms to this transshipment point awaiting re-transport over land to Gaza or to other points in Africa.”

It has since emerged that eight Israeli F-15 fighter jets bombed the Iranian weapons stockpile in Sudan that night. Israel also intercepted Iranian arms shipments in March 2014, when their navy stopped a commercial ship called the Klos-C which was filled with Syrian long range rockets.

In March 2011, it also intercepted the Victoria with Iranian C-704 shore-to-sea missiles onboard, reportedly destined for Gaza.

Iranian fingerprints have been noticed on illicit shipments across the region.

In October 2010, Nigerian security forces arrested Quds Force activists in Nigeria after intercepting a shipment of mortar shells and rockets destined for Gambia.

In January 2009, the USS Farragut helped intercept in the Red Sea a former Russian ship filled with explosives that originated in Iran. It was escorted to Cyprus, where the contents of the cargo later exploded, killing a senior officer in the Cypriot Navy and leaving a 600 yard wide crater.