The new top US commander in Iraq said Saturday that the stakes are high but the situation is "not hopeless" as American and Iraqi forces move to quell spiraling sectarian violence in the country. Gen. David Petraeus made the comments at a ceremony during which he officially took control of US forces in Iraq from Gen. George Casey, who is going to be the next Army chief of staff. "The stakes are high. The way ahead will be hard but it is not hopeless," he said. "We can and we must prevail. This mission is doable."