WASHINGTON — A new assessment by U.S. intelligence agencies predicts that American influence in the world will decline over the next two decades as surging powers such as China and India, as well as independent entities including tribes and criminal networks, gain international clout.
The report, meant to serve as a guidepost for President-elect Barack Obama's administration, offers a vision of a future in which the U.S., while the most powerful, is but "one of a number" of important players in the world.
Describing the findings, Tom Fingar, deputy director of National Intelligence for analysis, said there would be a "diminished gap between the United States and everybody else. . . . The unipolar moment is over."
The report, titled "Global Trends 2025: A Transformed World," represents the U.S. intelligence community's most comprehensive examination to date of long-term security issues. It sees a possible increase in terrorist violence even as support for extremism starts to wane.
Its central finding is that the U.S. will remain the world's foremost economic and military force, but its standing as an unrivaled superpower will probably diminish as a "global multipolar system" emerges.
China stands to have more effect on the world over the next 20 years than any other country, the report says, and India will strive to represent one of the world's economic poles.
How the world adjusts to their new roles will be up to the two countries, the report says.
"China and India must decide the extent to which they are willing and capable of playing increasing global roles and how each will relate to the other," the report says.
Japan could be caught between U.S. and Chinese influence, and Russia could grow or stall, depending on the economic decisions it makes, the report says. Brazil is poised to gain in influence and wealth.
The spread of influence could lead to larger roles for countries such as Iran, Indonesia and Turkey, the report adds.
The overall result will leave "less room for the U.S. to call the shots," the report says, and U.S. military power will be limited by the growing use by others of irregular warfare tactics and the proliferation of long-range precision weapons.
The document predicts the international alliances and networks that have dominated global affairs since the end of World War II "will be almost unrecognizable by 2025."
For years, U.S. analysts have anticipated that China, India and other emerging economic powers will gain international influence. But the report warns of another, possibly destabilizing, dynamic.
"The relative power of non-state actors -- businesses, tribes, religious organizations and even criminal networks -- will grow as these groups influence decisions on a widening range of social, economic and political issues," the report says.
The U.S. intelligence agencies compile reports on global trends every four years, and they have proved prescient.
In 2000, as George W. Bush was waiting to take office, a global trends report warned about the threat of large-scale terrorist attacks, noting that year's strike on the U.S. warship Cole.
"Such asymmetric approaches -- whether undertaken by states or non-state actors -- will become the dominant characteristic of most threats to the U.S.," the 2000 report said.
The document released Thursday, available at www.dni.gov, examines an array of global issues, including climate change, economic dislocation and Islamic radicalism.
On terrorism, the report offers a mixed verdict. It concludes that Al Qaeda and other extremist terrorist groups face declining support across the Middle East and in other parts of the Muslim world.
But it warns that terrorist organizations will probably become more deadly because the spread of chemical and biological technologies "will place some of the world's most dangerous capabilities within their reach."
The report concludes that Al Qaeda will probably pose a lasting threat to the U.S. and other Western nations. But it cites the view of some experts that Al Qaeda "suffers from strategic weaknesses that could cause it to decay into marginality, perhaps shortening the life span of the Islamic terrorist wave."
Analysts said one factor that could lead to such an outcome is Al Qaeda's lack of a compelling vision that moderate Muslims might favor.
The report characterizes Al Qaeda's tactics and objectives -- including the use of violence against Muslims, strict observance of Islamic law and the subjugation of women -- as factors that undermine its long-term viability.
"The appeal of terrorism is waning," said Mathew J. Burrows, a member of the National Intelligence Council who played a leading role in drafting the report. "However, the lethality of terrorist groups is likely to grow."
The report touches briefly on the global economic crisis, concluding that it is not likely to lead to an extended depression but is accelerating "the global economic rebalancing."