What is the true value of a foreign power placing an agent in the president's circle?

The obvious answer would seem to be the potential to steal highly classified information and pass along the nation's most intimate secrets. But in a Halloween speech [PDF] more than 30 years ago, then-CIA Director William Casey offered a different answer: Influence.

Casey used as his example the case of Alger Hiss, an infamous former State Department official who was convicted in 1950 of perjury related to his work as a Soviet spy.

"If I have any theme, it is that it is not quite accurate to think of Alger Hiss as a mere Russian spy. His role as an agent of influence is far more meaningful to us," Casey told his audience in 1984. "He did steal and pass along... some information about Japanese troop movements in Manchuria, French military supplies in Rumania, and such things in the late thirties. How trivial this seems compared to the Soviets having, at the end of World War II, an agent of influence close to the major policymakers in Washington.

"How the KGB must have preened itself at the photos of the smiling Alger Hiss standing behind Roosevelt, [Soviet leader Joseph] Stalin, and [British Prime Minister Winston] Churchill at Yalta and welcoming Harry Truman to the podium for the first address of an American President to the UN. How trifling the theft of some papers passing over his desk when matched up against the opportunity to whisper into the ears of American leaders and counsel them on their policies."