W HAT the British public sees of Cabinet reshuffles is limited to the sight of hopeful or doleful ministers entering No 10 Downing street, after waving at the TV cameras and press photographers. By contrast, on Wednesday in the White House Rose Garden and in front of national TV, President Obama introduced his new National Security Adviser, Susan E Rice, and her successor as Ambassador to the United Nations, Samantha Power. For both he had informal but impressive praise as being committed to humanitarian intervention and, by implication, as advocates of caution in getting involved in foreign conflicts. Ms Power was a journalist in Bosnia during the Balkan Wars; Ms Rice has said that the Rwandan massacres were a turning point for her view of foreign policy objectives. Their appointments followed the planned retirement of Tim Donilon after more than three years as National Security Adviser; he was present in the Rose Garden and heard the President pay rich tribute to his service. The appointment of Susan Rice is a rebuff to the Republican Party in Congress which still continues to associate her with the administration's handling of the Benghazi incident last September in which the American Ambassador to Libya was killed. She was in line as Hillary Clinton's successor as Secretary of State but withdrew because of fierce Republican hostility towards her. The President has re-affirmed that he has confidence in her.