In its determination to secure a nuclear deal with Iran, the Obama administration derailed an ambitious law enforcement campaign targeting drug trafficking by the Iranian-backed terrorist group Hezbollah, even as it was funneling cocaine into the United States, according to a POLITICO investigation.

The campaign, dubbed Project Cassandra, was launched in 2008 after the Drug Enforcement Administration amassed evidence that Hezbollah had transformed itself from a Middle East-focused military and political organization into an international crime syndicate that some investigators believed was collecting $1 billion a year from drug and weapons trafficking, money laundering and other criminal activities.

Over the next eight years, agents working out of a top-secret DEA facility in Chantilly, Virginia, used wiretaps, undercover operations and informants to map Hezbollah’s illicit networks, with the help of 30 U.S. and foreign security agencies.

They followed cocaine shipments, some from Latin America to West Africa and on to Europe and the Middle East, and others through Venezuela and Mexico to the United States. They tracked the river of dirty cash as it was laundered by, among other tactics, buying American used cars and shipping them to Africa. And with the help of some key cooperating witnesses, the agents traced the conspiracy, they believed, to the innermost circle of Hezbollah and its state sponsors in Iran.

But as Project Cassandra reached higher into the hierarchy of the conspiracy, Obama administration officials threw an increasingly insurmountable series of roadblocks in its way, according to interviews with dozens of participants who in many cases spoke for the first time about events shrouded in secrecy, and a review of government documents and court records. When Project Cassandra leaders sought approval for some significant investigations, prosecutions, arrests and financial sanctions, officials at the Justice and Treasury departments delayed, hindered or rejected their requests.

The Justice Department declined requests by Project Cassandra and other authorities to file criminal charges against major players such as Hezbollah’s high-profile envoy to Iran, a Lebanese bank that allegedly laundered billions in alleged drug profits, and a central player in a U.S.-based cell of the Iranian paramilitary Quds force. And the State Department rejected requests to lure high-value targets to countries where they could be arrested.