Just after midnight on October 24, a series of loud explosions shook a neighborhood on the southern outskirts of the Sudanese capital, Khartoum. Within minutes, flames shooting skyward illuminated the area, and the Yarmouk Industrial Complex was consumed by fire.
Witnesses said they heard planes in the area, and a subsequent analysis of satellite images revealed six large craters "each approximately 16 meters [52 feet] wide ... and consistent with craters created by air-delivered munitions," according to the Satellite Sentinel Project, a non-governmental organization that analyzed DigitalGlobe imagery.
As the smoke cleared the next day, Sudanese officials blamed Israel for the airstrike, which destroyed a large part of the complex, including an ammunition plant and some 40 shipping containers.
The Satellite Sentinel Project said: "Nothing remains of the 60-meter [197-foot] building, which appears to have been pulverized in the blast."
The Israelis said nothing. But the devastating strike appears to have been the latest episode in a shadowy war between Israel and at least two of its enemies: Iran and Hamas.
United States, Israeli and Egyptian officials have long suspected that Iran is using Sudan to smuggle weapons and equipment to Hamas, using a circuitous route by air into Khartoum or by ship into Port Sudan. Then the weapons start a long road trip through eastern Sudan, across the Egyptian border and up through the Sinai Peninsula to Gaza.
An Israeli official told CNN Monday that missiles and their components continue to be shipped through tunnels from Sinai into Gaza. He said Iran was providing munitions, Grad missiles, anti-aircraft missiles, communications, and command and control capability to Hamas.
His comments were echoed by one of the most powerful tribal figures in northern Sinai, Ibrahim Menai.
Menai, who reportedly owns several of the smuggling tunnels that connect Sinai with Gaza, told CNN late Monday: "Weapons that are smuggled to Gaza come mostly from Sudan and recently from Libya during the security vacuum that followed the revolution in Egypt."
"Bedouin who are involved in arms smuggling receive the weapons from Sudan on small fishing boats through the Red Sea and by land through rugged mountain terrain only familiar to them and are almost impossible to intercept by security forces who have little power over the Bedouin community," he said.
"The weapons that are smuggled to Gaza are mostly Grad missiles, anti-aircraft missiles, and recently during the Libyan revolution, advanced shoulder held anti-tank missiles came through," he said.
Menai also says it's very likely that the long-range Fajr-5 missiles have been smuggled through from the Egyptian side, "most likely hidden among other merchandise that is loaded onto big trucks that go through the big tunnels."
Last month, an Iranian diplomat at the United Nations said the allegation that Iran was using Sudan to supply Hamas with weapons was "totally unfounded, and we strongly reject these baseless allegations." Sudan has also denied "any link between Sudan's military production and foreign parties," according to its Foreign Ministry.
But in an interview with a Qatari newspaper earlier this month, Iran's Foreign Minister Ali Akbar Salehi said: "Let's assume that Iran has established an arms factory in Sudan. Is this forbidden? Within the framework of international laws, if there is a country that wants to buy weapons from us, we are ready."
The Yarmouk plant was "designated" by the United States as essentially under the control of Iran at the end of 2006 and thereby became the target of sanctions under the Iran and Syria Nonproliferation Act.
The strike on the night of October 24 was one of four unexplained attacks over the past three years against targets in Sudan.
Early on the morning of May 2, a Toyota Prado exploded on the outskirts of Port Sudan on the Red Sea, a city that Western intelligence agencies believe is a critical point on the smuggling route. Sudanese officials identified one of the victims as Nasir Awad Ahmad Saed, a wealthy businessman and tribal leader.
Sudan's foreign minister, Ali Ahmad Karti, suggested that the car was destroyed by an airstrike and told a pro-government network that the attack resembled previous Israeli attacks. Why Saed would have been targeted is unclear.
In a similar attack in Port Sudan a year earlier, a man who had just arrived at the city's airport was killed. Karti said at the time: "We know that it was an Israeli strike." But he denied the target was a Palestinian.
And in January 2009, a convoy of more than a dozen vehicles traveling between Khartoum and Port Sudan was hit and destroyed in an aerial attack.
The Sudanese transport minister, Mabrouk Mubarak Saleem, said soon afterward that a "major power bombed small trucks carrying arms, burning all of them." Unconfirmed reports at the time said the vehicles were carrying components of Iranian-made Fajr-3 missiles, which have a range of some 65 kilometers (40 miles).
A review of U.S. diplomatic cables published by WikiLeaks suggests that Iranian weapons shipments to Gaza via Sudan became an issue in 2007.
Early in 2009, Israeli Prime Minister Benjamin Netanyahu told a visiting U.S. congressional delegation: "The Egyptians know that the arms pipeline runs from Iran to Sudan to Egypt.....the Egyptians could do more to stop it, but at least they now grasp the extent of the threat."
At the same time, the deputy chief of staff of the Israel Defense Forces, Maj. Gen. Dan Harel, urged the U.S. to prod Cairo to do more, and soon, because "Hamas was getting more sophisticated weaponry from Iran, to include longer-range missiles."
Despite the convoy attack, suspicions persisted that Iran was still shipping arms to Sudan. In July 2009, the United States pressed Jordan to deny overflight rights to some planes traveling between Khartoum and Iran, including some operated by a private freight carrier, Badr Airlines, which is based in the Sudanese capital.