The arrests targeted a division of Hezbollah, a Lebanese militant organization, that provides "a revenue and weapons stream ... responsible for devastating terror attacks around the world," DEA Acting Deputy Administrator Jack Riley said in a statement.
Seven countries, including France, Germany, Italy and Belgium, were involved in the operation, which apprehended four individuals. The investigation began last February, with the DEA saying that additional arrests were likely.
The terrorist network was said to be working with South American drug cartels to facilitate the movement of millions of dollars in cocaine to the United States and Europe, according to the DEA statement.
The DEA accused the group of using the proceeds of these drug sales to purchase weapons for Hezbollah for its activities in Syria. Hezbollah has sent thousands of fighters to bolster the Syrian regime of President Bashar al-Assad.
Hezbollah also receives weapons and financial support from Iran, but experts said that a combination of factors had increased the terrorist group's reliance on revenue from criminal activity.
"Defending the Assad regime in Syria is a drain on personnel, funds, and military resources," terrorism expert Matt Levitt of the Washington Institute for Near East Policy told CNN.
The decline in oil prices has led Iran to cut back support, forcing Hezbollah to reduce salaries, and one of the motivating factors behind Hezbollah's embrace of criminal activity has been its desire to "reduce its financial reliance on Iran," Levitt said.
Last week, the Treasury announced a series of sanctions targeting the financial support network for Hezbollah, which the State Department has designated a foreign terrorist organization.
The group has a long history of attacks, including one at the U.S. Marine barracks in Beirut, Lebanon, in 1983 that killed 241 Americans. Hezbollah has also been linked to terrorist plots against Israelis in Bulgaria in 2012 and Peru in 2014.
DEA spokesman Rusty Payne told CNN that the terrorist network was laundering the drug money through the acquisition and sale of high-end used cars, sometimes hiding the cash inside the vehicles themselves as they were shipped internationally.