Large majorities in many Asian countries fear that China's territorial ambitions could lead to war, according to the Pew Research Center, in a finding with implications for U.S. foreign policy in a region that increasingly looks to America for protection.
A widespread worry that military conflict over territorial disputes may disrupt the region is among the findings of a public-opinion survey of 44 countries by the Washington-based Pew.
Another global trend is building opposition to U.S. eavesdropping following revelations of spying by former National Security Agency contractor Edward Snowden. U.S. drone strikes also elicit strong misgivings. However, those controversies don't appear to have done too much damage to America's generally positive global image, outside the Muslim world, the Pew report said.
The survey, conducted from March to June, comes after China has muscularly pressed its claims over disputed islands, sending ships, planes and, in one case, an oil rig into areas held or contested by several neighbors.
Fears of armed conflict are at high levels among those countries locked in these standoffs with China, according to responses to a question introduced this year in Pew's spring survey of global attitudes. In the Philippines, 93% of respondents are concerned about an outbreak of hostilities. In Japan, the figure is 85%, and in Vietnam, 84%.
Yet worries about China's threat to peace are almost as strong in South Korea, a close neighbor that has warm relations with China, where 83% of respondents fret about war. Even in China, 62% are anxious.
Protesters in the Philippines denounced China's deployment of an oil rig in disputed South China Sea territory in May. Associated Press
Among the 11 Asian countries surveyed, majorities in nine were concerned about armed conflict.
China's actions to assert what it regards as its legitimate territorial rights have stopped just short of the point where they might trigger armed conflict with Japan and other U.S. allies and new friends like Vietnam—and potentially entangle the U.S. itself.
The U.S. is growing increasingly alarmed at China's use of coercion in a part of the world where it has vital trade and security interests. The survey showed 67% of Americans are also concerned about conflict.
After a long spell of "smile diplomacy" to woo its neighbors, China has over the past two years shown a different face. Chinese ships and warplanes have been intruding into waters surrounding the Senkaku Islands in the East China Sea that are controlled by Japan but claimed by China, which calls them the Diaoyus. Chinese paramilitary vessels have fenced off the Scarborough Shoal, a fishery haven off the Philippines coast and are putting pressure on a small contingent of Philippine marines defending a speck of territory called the Second Thomas Shoal. This spring, China positioned an oil-drilling rig off the Paracels, a set of islands disputed with Vietnam.
The Pew findings underscore how China's perceived bullying is driving countries in the region into America's embrace. Eight of 11 Asian countries surveyed see America as their No. 1 ally. Three perceive the U.S. as the major threat—China, Malaysia and Pakistan—while one, Indonesia, counts the U.S. as both an ally and a threat.
Underlying the tensions is the fact that China's economic rise, while an undisguised blessing for most Asian countries, is also spurring Chinese military spending and shifting the balance of power toward China in a region that has relied on U.S. security guarantees to underpin its stability. Asian security experts and some politicians have voiced concern about how a powerful China intends to wield power in the future.
All this is exacerbated by perceptions that America's long-term economic prospects are declining. Around the world, according to Pew, there is a gathering perception that China is overtaking the U.S.
Based on a smaller sample of 20 countries surveyed in 2008, before the global financial crisis erupted, and again this year, the median percentage naming the U.S. as the world's leading economic power has dropped to 40% from 49% six years ago, while the percentage naming China has risen to 31% from 19%.
Meanwhile, 50% of that narrower sample now believes that China will eventually replace the U.S. as the pre-eminent superpower—or has already replaced it—up from 41% in 2008. Only 32% believe the switch will never take place.
Overall, though, America is still more popular than China. A median 65% of the publics surveyed hold a positive view of the U.S. versus 49% for China.
This is despite Mr. Snowden's spying revelations, which has led to a decline in those saying that America respects the personal freedoms of its people. U.S. President Barack Obama remains popular, with a median of 56% having confidence in him to do the right thing in world affairs. Interestingly, his stock is rising sharply in China, where 51% give him the thumbs up. But his ratings have plummeted in Germany—to 71% this year from 88% last year—where there is mounting anger over the way the U.S. has listened in to the phone calls of national leaders.
The Pew report also finds rising misgivings about American drone attacks. In 39 of 44 countries surveyed, majorities or pluralities oppose U.S. drone strikes targeting extremists in countries such as Pakistan, Yemen and Somalia.
Write to Andrew Browne at andrew.browne@wsj.com