Arms dealer Jacques Monsieur was jailed by a U.S. court for plotting to smuggle jet engines to Iran but, with the Islamic Republic smarting under a new Russian arms ban and international sanctions, Tehran's going to need suppliers like Monsieur more than ever.

The swashbuckling Monsieur, a veteran gunrunner and former intelligence agent known as The Field Marshal, pleaded guilty in a Mobile, Ala., court and was given a 2-year prison sentence Friday after a plea bargain.

After 13 months behind bars since his arrest in New York Aug. 27, 2009, he will only have to spend about 10 months more in prison for conspiracy to smuggle U.S.-made J85-21 engines for F-5 fighter jets to the Islamic Republic.

The Belgian-born Monsieur is only one of a score of people convicted in recent months of involvement in smuggling weapons, along with missile and nuclear components, to Iran, in most cases from the United States.

The Americans have led a global campaign to cripple Iran's clandestine arms-purchasing network and the gunrunners defying U.N. and U.S. arms bans on Iran.

But Tehran has established a global network of people like Monsieur and a web of shell companies distant from Iran in Malta, Samoa, Cyprus, Hong Kong, the United Arab Emirates and Britain's Isle of Man to disguise its purchases.

These companies, which sometimes operate only for a few weeks, are often run out of Iranian embassies in Europe. The purchases include high-tech components so Iran's burgeoning arms industry can produce its own weapons systems.

Last week, Russian President Dmitry Medvedev agreed to ban the sale of Russian missiles, aircraft, tanks, armored vehicles and artillery, along with spares, to Iran because it refuses to abandon its nuclear program. That cut off a vital source of arms for the Iranians.

On top of a fourth round of U.N., U.S. and EU sanctions on Iran in recent weeks, Tehran will have to turn to the gunrunners and its network of clandestine arms buyers to help its drive to upgrade its military forces.

The Islamic Republic has had to conduct much of its arms procurement secretly almost from the moment Shah Mohammad Reza Pahlavi, armed to the teeth by the Americans, was toppled in January 1979.

According to former U.S. Justice Department official Pat Rowan, who tracked Iran's arms-buying operations, Tehran depends to a large extent on middlemen running "shady companies around the world.

"It's an extraordinary network they've developed to work around the web of sanctions that's intended to stop them."

This network was given great impetus by the 1980-88 war with Iraq, when ensuring a steady supply of weaponry became crucial for the infant republic's survival after Saddam Hussein invaded.

These days the procurement network is largely controlled by the Intelligence Ministry and the Revolutionary Guards Corps, which also controls the defense industry.

They report to President Mahmoud Ahmadinejad and Iran's supreme leader, Ayatollah Ali Khamenei.

According to Claude Moniquet, president of the European Strategic Intelligence and Security Center, a Brussels think tank that monitors international terrorism, the network is still mainly run by the Iranian embassies in Berlin and Paris.

"The scientific counselor of the embassy in Paris is a post which is usually occupied by an intelligence officer charged with industrial and scientific espionage," he said in a recent analysis.

"He performs this function for the entire European Union with the exception of Great Britain."

In June 2005, the U.S. Justice Department said that it had thwarted several plots that prevented arms worth $2.5 billion, including 18 F-4 and 13 F-5 fighter jets, 20 helicopters and thousands of missiles of various types, reaching Iran.

Among those indicted was a Samuel Evans, a 50-year-old U.S. corporate lawyer based in London and a retired Israeli army general, Avraham Baram. It was the biggest arms bust U.S. authorities had ever made.

One of the big fish the Americans caught was Amir Hossein Ardebili, an Iranian engineer arrested in October 2007 in a sting operation run by U.S. agents. On Dec. 15, 2009, he was jailed for five years by a U.S. court on 14 counts of violating U.S. arms control regulations. Court documents described him as a "prolific" arms buyer for Tehran.