"We face significant challenges from Iran, which has repeatedly shown its unwillingness to play a responsible and constructive role in the international community. By working with the UN Security Council and with the broader international community, the administration has sent a strong message to Iran that it needs to address the very serious and urgent concerns about the nature and extent of its nuclear program. These sanctions must now be enforced and strengthened. At the same time, it is important to remember that sanctions are meant to be a tool towards the resolution of the Iranian nuclear problem, not an end in themselves, and I hope that this hearing will provide a better picture of our broader strategy and plans going forward."