Dittrich was given his mission: to establish contacts with foreign policy think tanks, and in particular President Carter’s national security adviser, Zbigniew Brzezinski. He was given little guidance as to how he should do this, or even how best to blend into US society. The people who trained him had little feeling for the real fabric of America, its visceral, unquantifiable essence. “It’s as if they had spent time looking at fish swimming in an aquarium, and now they are training you to be a fish,” Barsky says. “But they don’t actually know what it’s like to be a fish.”
The book Deep Undercover by Mr. Barsky says that he was expected to establish contacts with people connected to "influential think tanks such as the Hudson Institute, the Columbia University Institute of Foreign Relations, and the Trilateral Commission."
Think tanks have been a hotbed a spy recruitment for decades. Here is a previous Think Tank Watch post on which think tanks spies like. It is no secret that think tanks are filled with former spies.
While human intelligence still goes on at think tanks, these days much of the spying is done through signals intelligence, with nearly every single large think tank facing serious breaches in recent years.
Here is a recent story by Molly Ball on Washington spy paranoia, with several mentions of think tanks.