I ran across this post based on a series of 2010 interviews with Tyler Drumheller in which he discussed South Africa’s nuclear weapons program:

During our interviews, he reflected on earlier experiences in his career. In 1980, “we had 11 case officers in South Africa, four of them with deep cover.” They had penetrated the apartheid regime’s “Project Circle,” which was already within reach of perfecting a usable, deliverable atomic bomb.

“We were regularly able to obtain swipe samples from its enrichment facilities. We could monitor progress,” Drumheller told me.

They also monitored the deep cover “black station” of Israel’s intelligence agency, the Mossad. Drumheller said this was a front company called TamCo. The Israelis had no idea they were under such close U.S. scrutiny.

Washington had tried to impede Pretoria’s effort by embargoing the shipment of a VAX computer from Massachusetts-based Digital Equipment Corporation. “Project Circle needed that VAX” to complete the project, Drumheller said.

The CIA station in Pretoria learned that South Africa was able to get around the embargo by having the computer — the same powerful VAX model — transshipped from the United States. “It came via the Israelis and TamCo,” Drumheller said.

[snip]

The CIA was able to obtain these and other details about the Israeli-South African collusion, Drumheller explained, from a stellar agent that the CIA had placed within Project Circle.