[cnn-photo-caption image= http://i2.cdn.turner.com/cnn/2009/images/01/26/art.riceshake0126.gi.jpg caption="Dr. Susan Rice, new U.S. ambassador to the U.N., met with U.N. Secretary-General Ban Ki Moon Monday."]
UNITED NATIONS (CNN) - President Barack Obama's ambassador to the United Nations, Susan Rice, arrived for her first day on the job Monday calling the U.N. a "great institution" but saying there is "room for improvement."
Watch: Rice vows cooperation
Rice presented her credentials to U.N. Secretary-General Ban Ki-moon at U.N. headquarters in New York Monday morning. She said the two then spoke for 45 minutes, discussing a wide range of international issues, including the situations in Sudan and the Middle East.
After meeting with Ban, Rice spoke to reporters in front of the U.N. Security Council chambers, laying out several key issues that the Obama administration hopes to accomplish at the United Nations: Strengthening the capacity to engage in complex peace operations, advancing U.S. and "collective" interest on climate change and nuclear proliferation, and putting the United States at the center of poverty reduction and fighting disease, cornerstones of the U.N. Millennium Development Goals.
On the issue of U.S.-Iranian relations, Rice expressed concern about the "threat of Iran's nuclear program" and emphasized that vigorous diplomacy and dialogue must go hand in hand with a direct message from the international community that Iran's nuclear program must come to an end.
Rice said the United States is prepared for direct diplomacy with Iran, along with supporting the stalled, multilateral efforts of Western European powers, Russia, and China with Tehran.
On the Middle East, Ambassador Rice reiterated Obama's expression of "grave concern" about the humanitarian situation in Gaza, which will be discussed in the Security Council on Tuesday. Rice emphasized the U.S. position on conflict between Hamas and Israel, calling for a durable cease-fire.
Rice, an African affairs expert, also addressed the conflict in the Darfur region of western Sudan, expressing deep concern about the "ongoing genocide" there.
She said U.S. attention will be focused on protecting civilians in Darfur, and the United States will effectively support the work of UNAMID, the joint United Nations-African Union peacekeeping force in Darfur. That deployment is currently dramatically underfunded and under-supported by U.N. member states, despite repeated calls by Ban for more material support.