US President George W. Bush headed to southern India on Friday, a day after he sealed pact to usher India into the world's exclusive nuclear club in return for New Delhi's acceptance of international safeguards. The accord, reached Thursday during a three-day visit to India by Bush, would end India's long isolation as a nuclear maverick that defied world appeals not to develop nuclear weapons. It represents a reversal of policy for the United States, which placed sanctions on New Delhi after India joined rival Pakistan in testing nuclear weapons in 1998. India has agreed to separate its tightly entwined nuclear industry _ declaring 14 reactors as commercial facilities and eight as military _ and to open the civilian side to international inspections for the first time. In exchange, the United States will share reactors, fuel and expertise with India. But the pact must be approved by a skeptical US Congress, and Bush, who was heading to Pakistan later Friday, acknowledged it might be difficult to get the nuclear accord endorsed because India still refuses to sign the Nuclear Nonproliferation Treaty. "I'm trying to think differently, not stay stuck in the past," said Bush, who has made improving relations with India a goal of his administration. Celebrating their agreement, Indian Prime Minister Manmohan Singh said, "We have made history today, and I thank you." The US-India nuclear deal was seen as the centerpiece of better relations between the world's oldest and most powerful democracy and the world's largest and fastest-growing one. The United Nations' nuclear watchdog agency, the International Atomic Energy Agency, gave its endorsement Thursday, calling the deal "an important step towards satisfying India's growing need for energy, including nuclear technology and fuel, as an engine for development." "It would also bring India closer as an important partner in the nonproliferation game," IAEA Director-General Mohamed ElBaradei said in a statement. However, Australia announced Friday that it would continue to bar its uranium sales to India until it signs the Nuclear Nonproliferation Treaty. India has more than 1 billion people, and its booming economy has created millions of jobs along with consumer demands that have attracted American businesses. India's middle class has swelled to 300 million - more than the population of the United States. Bush acknowledged that Washington and New Delhi were estranged during the Cold War, when India declared itself a nonaligned nation but tilted toward Moscow. "Now the relationship is changing dramatically," he said. But even with Bush more popular in India than many other countries, opposition to the American president and his administration's policies - especially in Iraq and Afghanistan - remains. In the southern city of Hyderabad, where Bush arrived aboard Air Force One on Friday morning, communist parties and Muslim groups have called for a day-long strike and rallies to protest the American president's visit, which was to include a trip to an agricultural college. Security in Hyderabad was tight, with police and paramilitary soldiers deployed throughout the city. In the predominantly Muslim Charminar quarter, shops were shuttered and black flags flew over houses and buildings. Banners in English and Urdu that read, "Bush, the enemy of human rights," were strung over streets. At a park in the center of the city, hundreds of communists waved red flags as they gathered for a march through town. "We are protesting against George Bush because he is a warmonger. We are demanding the evacuation of American troops from Iraq," said B.V. Raghavulu, a leader of the Communist Party of India (Marxist). Many also criticized the nuclear deal as a sellout to the Americans. Bush said helping India with nuclear power would reduce the global demand for energy which has sent gasoline prices soaring. It also could be a boon for American companies that have been barred from selling reactors and material to India. Critics have complained the deal rewards bad behavior and undermines efforts to prevent states like Iran and North Korea from acquiring nuclear weapons. The White House said India was unique because it had protected its nuclear technology and not been a proliferator.