"Pakistan must understand that they are choosing the wrong side," Paul said. "They accuse Dr. Afridi of working against Pakistan, but he was simply helping the U.S. capture the head of al Qaida. Surely Pakistan is not linking their interests with those of an international terrorist organization."

Afridi helped the CIA by running a vaccination drive to try to get DNA samples from those living inside the bin Laden compound. While he was unsuccessful, U.S. officials say he aided the intelligence operation.

The Senate Appropriations Committee already cut aid to Pakistan by $33 million in reaction to Afridi's sentencing, but Paul wants more action.

"Foreign aid has been an abysmal failure precisely for this reason — we give the aid to governments who then turn and work against our national interest," Paul said. "That must end."

He said he'd also introduce a bill granting Afridi U.S. citizenship when he's released from Pakistani custody.