AlHijjah 21, 1432, Nov 17, 2011, SPA -- President Barack Obama said Thursday the United States was switching focus to the Asia-Pacific region now. "After a decade in which we fought two wars that cost us dearly in blood and treasure, the United States is turning our attention to the vast potential of the Asia-Pacific region," he told the Canberra Parliament on the second and last day of a visit to Australia. Obama pledged that defence spending cuts would not be visited on its forces in the region. "Reductions in US defence spending will not - I repeat will not - come at the expense of the Asia-Pacific," he said. "We will preserve our unique ability to project power and deter threats to peace. We will keep our commitments, including our treaty obligations to allies like Australia." Australia and the US have agreed that the far-north garrison town of Darwin would host 250 US Marines on six-month rotations from next year with numbers rising to 2,500 within five years. The updating of the 60-year-old formal military alliance will also give greater access to US military aircraft. "With most of the world's nuclear powers and some half of humanity, Asia will largely define whether the century ahead will be marked by conflict or cooperation, needless suffering or human progress," Obama said. "As president, I've therefore made a deliberate and strategic decision - as a Pacific nation, the United States will play a larger and long-term role in shaping this region and its future, by upholding core principles and in close partnership with our allies and friends." In his remarks, Obama said he expected international norms to be upheld in the region. "We stand for an international order in which the rights and responsibility of all nations and all peoples are upheld, where international law and norms are enforced, where commerce and freedom of navigation are not impeded, where emerging powers contribute to regional security and where disagreements are resolved peacefully," Obama said. Obama left from Darwin to attend a regional conference in Bali, Indonesia.