"The diffusion of power among countries will have a dramatic impact by 2030," says the fifth installment in the US National Intelligence Council's series aimed at providing a framework for thinking about the future released here Monday.
The report "Global Trends 2030: Alternative Worlds," released by the Office of the Director of National Intelligence, the apex body of 16 US intelligence agencies, says China alone will probably have the largest economy, surpassing that of the United States a few years before 2030.
"In a tectonic shift, the health of the global economy increasingly will be linked to how well the developing world does-more so than the traditional West," the report said.
"In addition to China, India, and Brazil, regional players such as Colombia, Indonesia, Nigeria, South Africa, and Turkey will become especially important to the global economy.
"Meanwhile, the economies of Europe, Japan, and Russia are likely to continue their slow relative declines," the report said.
Despite their growing economic clout, developing countries will face their own challenges, especially in their efforts to continue the momentum behind their rapid economic growth, it said.
With slowing growth China "faces the prospect of being trapped in middle-income status, with its per capita income not continuing to increase to the level of the world's advanced economies."
"India faces many of the same problems and traps accompanying rapid growth as China: large inequities between rural and urban sectors and within society; increasing constraints on resources such as water; and a need for greater investment in science and technology to continue to move its economy up the value chain," the report said.
"Insufficient natural resources - such as water and arable land - in many of the same countries that will have disproportionate levels of young men increase the risks of intrastate conflict breaking out, particularly in Sub-Saharan African and South and East Asian countries, including China and India," it said.
"Three different baskets of risks could conspire to increase the chances of an outbreak of interstate conflict: changing calculations of key players- particularly China, India, and Russia; increasing contention over resource issues; and a wider spectrum of more accessible instruments of war."
South Asia, the report said: "faces a series of internal and external shocks during the next 15-20 years. Low growth, rising food prices, and energy shortages will pose stiff challenges to governance in Pakistan and Afghanistan."
"Afghanistan's and Pakistan's youth bulges are large-similar in size to those found in many African countries. When these youth bulges are combined with a slow-growing economy, they portend increased instability."
However, it said, "India is in a better position, benefiting from higher growth, but it will still be challenged to find jobs for its large youth population. Inequality, lack of infrastructure, and education deficiencies are key weaknesses in India."
How the United States' international role evolves during the next 15-20 years was a big uncertainty, the report said.
"Whether the US will be able to work with new partners to reinvent the international system will be among the most important variables in the future shape of the global order," it said.