NEW YORK - Anyone worried about an erosion of America's global status might consider this modest fact: Facebook is the dominant social network in Mongolia.

Along with its pervasive social media, the United States leads in myriad other ways - from the allure of its movies and music to the reach of its military. It's tough to match a nation that deploys troops to Australia and central Africa, propels Beyonce to global stardom, and produced the Twitter-style technologies that abetted the Arab Spring.

"American entrepreneurs are defining the digital age," said Harald Leibrecht, the German government's coordinator for U.S. relations. "And when looking for the 'next big thing,' we very much expect it to come from over the Atlantic as well."

So what's with all the talk about America in decline? There seems to be a forest's worth of recent books raising that possibility, with gloomy titles such as "That Used to be Us." Republican presidential candidate Mitt Romney suggested that President Barack Obama considers the U.S. "just another nation."

Abroad, foreign policy experts are following this discussion with a mix of bemusement and concern. A dozen of them, in nine countries on five continents, shared their thoughts with The Associated Press - agreeing that the U.S. stands alone as a global superpower, yet perceiving an array of weaknesses that could undermine its stature as numerous emerging powers seek a bigger role on the world stage.

Cited most often: the partisan political gridlock in Washington - viewed as hindering efforts to tackle other long-term problems.

"Some U.S. vulnerabilities are quite obvious," said Dmitri Trenin, a Russian expert on diplomatic and security policy, in an email from Moscow. "The issue of debt ... too loose financial regulation, social inequality which is punishing America's middle class."

Trenin, director of the Carnegie Moscow Center, predicted the U.S. will nonetheless remain pre-eminent for decades, yet questioned the ability of America's political elite to interpret and respond wisely to global developments.

"This is not always impressive, and some comments made on the election stump are downright depressing," he said.

Narushige Michishita, a professor at Tokyo's National Graduate Institute for Policy Studies and adviser to Japan's government on security issues, views the debate in the U.S. over its global stature as a sign of insecurity. He says it has prompted to Japan to look to other strategic partners to bolster its position in Asia.

"It is clear in relative terms that the U.S. is starting to decline in comparison with China," said Michishita. "As U.S. commitment and influence starts to decline ... it is inevitable China will expand."

China, for all its size and rapid economic growth, is decades away from any plausible claim to equal stature. The U.S. dollar is still the world reserve currency of choice, and America will have far higher per capita income even when China - with more than four times as many people - eventually claims the world's largest economy.

Nonetheless, the latest global attitudes survey by the Pew Research Center, conducted last year, found that a majority of respondents in 15 of 22 nations believed China either will replace or already has replaced U.S. as the leading superpower. This view was especially prevalent in Western Europe - for example, held by 72 percent of French people.

Among Americans, the percentage saying that China will eventually overshadow or has already overshadowed the U.S. increased from 33 percent in 2009 to 46 percent in 2011.

What do China's experts say? The Chinese Academy of Social Science's Comprehensive National Power index - which weighs natural resources, population demographics, and military, scientific and economic strength - ranks the U.S. first and China at No. 7.

By some other measures, China fares worse - it places 101st in the United Nations' latest Human Development Index ranking countries according to life expectancy, educational attainment and income. The U.S. placed fourth after Norway, Australia and the Netherlands.

To some in China, the self-doubts in the U.S. seem overblown.

"The U.S. has a strong sense of crisis," said Zhu Feng, an international affairs expert at Peking University who frequently travels to the U.S.

Zhu's advice, when it comes to talk of China surpassing the U.S.: Don't believe the hype. By almost every measure, he notes, China still lags behind. It is investing billions in cutting-edge research, yet innovative spirit may at times be restrained by an oppressive political climate and a culture which values hierarchy and conformity.

"China is an adolescent power," Zhu said. "The most important lesson is to learn how to be a great power."

The United States has spent much of its existence learning how to be a great power - culminating with the post-Cold War era in which no single nation could rival it.

Yet the Republican presidential candidates often criticize Obama for what they perceive as a reluctance to embrace America's uniqueness.

One comment they seized on: Obama saying he believed in American exceptionalism, "just as I suspect that the Brits believe in British exceptionalism and the Greeks believe in Greek exceptionalism."

Another challenged remark, regarding the need to invest in infrastructure:

"We used to have the best stuff. Anybody been to Beijing Airport lately?" Obama said. "Well, we've lost our ambition, our imagination, and our willingness to do the things that built the Golden Gate Bridge and Hoover Dam."

Said Romney, during a campaign debate, "We have a president right now who thinks America's just another nation." GOP rival Newt Gingrich, author of a book titled "A Nation Like No Other," has made American exceptionalism a centerpiece of his campaign.

Obama has been blunt in rebuttal.

"Anyone who tells you that America is in decline or that our influence has waned, doesn't know what they're talking about," he said in his State of the Union speech.

The polemics have had a stimulus effect on at least one economic sector - a booming mini-industry of books engaging in the debate.

The titles often tell the tale: "The Post-American World" by journalist Fareed Zakaria; "That Used to Be Us" by New York Times columnist Thomas Friedman and foreign policy professor Michael Mandelbaum; "No One's World" by international affairs expert Charles Kupchan.

Friedman and Mandelbaum argue that the U.S. can recover its greatness, but only by aggressively tackling such challenges as globalization, budget deficits and excessive energy consumption.

Kupchan, a Georgetown University professor, argues that the dominance of the U.S. - and the West as a whole - is weakening in tandem with the rise of China, India, Brazil and other emerging powers.

"We're headed to a world for the first time in history that will be interdependent, globalized but without a political anchor," Kupchan told Book TV. "Most of the 21st century won't have a dominant player."

Even within the U.S. government, there's acknowledgment that America risks losing its edge in some sectors.

A Commerce Department report released in January said the economy's scientific and technological foundations have been eroding at a time when many other nations are growing stronger.

"In short, some elements of the U.S. economy are losing their competitive edge, which may mean that future generations of Americans will not enjoy a higher standard of living than is enjoyed in the United States today," the report warned.

The U.S. education system is slipping in some areas, such as students' training in math and science, according to the report. It said the U.S. is "lagging behind" in some vital aspects of 21st century infrastructure, such as broadband Internet access.

Another somber assessment came from a task force formed by the American Political Science Association - it concluded that America's global stature had "declined dramatically" over the past decade.

The task force chairman, Professor Jeffrey Legro of University of Virginia, said U.S. policymakers need to rethink budgetary priorities.

"All our money is going into entitlements," said Legro. "We need a rediversion of money into other areas - things that provide for the future, not for the past."