The simple answer is to bomb the reactors.
U.S. Intelligence: No Progress in Stopping Iran
(IsraelNN.com) Sobering words are coming from the US intelligence community. A new combined intelligence report from 16 American intelligence agencies, called the National Intelligence Estimate, says that it is unlikely there will be a change in the fundamentalist Iranian regime any time soon. Even worse, the report predicts little progress in the future in getting Iran to halt its nuclear program or stop supporting militant groups in the region. The U.S. has instituted a number of economic sanctions against the Iranian regime in the past couple of years.
Washington and Jerusalem estimate that Iran is capable of acquiring a nuclear bomb within one to three years.