In talks last week in Geneva, Iran agreed to fully cooperate with the United Nations' nuclear watchdog over its nuclear program. Progress in the talks with five permanent members of the U.N. Security Council — the United States, Russia, France, Britain and China — plus Germany represents a "constructive beginning," as U.S. President Barack Obama said. The talks and the agreement took place against the backdrop of Mr. Obama's attempt to establish a dialogue with Tehran, which has the capacity to play an important role in stabilizing the Middle East and Afghanistan. It is hoped that Iran will act with sincerity and follow through on the agreement.

Under the agreement, Iran will let International Atomic Energy Agency...