Countries across the world have a favorable view of the US and its fight against the Islamic State radical group, according to a Pew Research Center report.

America's use of torture, though, was widely condemned, with people in the 40 countries included in the study declaring the practice against suspected terrorists was not justified.

Internationally, the global median of public perception of the United States was 69 percent favorable and 24 percent unfavorable. The US airstrikes in Iraq and Syria against IS fighters drew 62 percent support and 24 percent opposition.

Those numbers were in stark contrast to the US invasion of Iraq in 2003, which was generally viewed unfavorably abroad.

But the US scored less favorably when people were questioned about what Pew called "the harsh interrogation methods used against suspected terrorists in the wake of 9/11 that many consider torture".

A median of 50 percent of global respondents felt the use of such tactics were not justified, compared to 58 percent of respondents in the US who felt the methods were warranted.

The use of torture was laid bare in a 2014 US Senate report about the interrogation of Al-Qaeda suspects following the September 11, 2001 terrorist attacks.

People around the world generally supported US President Barack Obama, with a median of 65 percent having confidence in the second-term leader.

The Pew report found people in Asia generally supportive of his plan to commit more military resources to the area.

The move has raised tensions between the US and China, which is angling for more control of the strategic South China Sea.

Favoring the US "pivot" to Asia were some 71 percent of people in the Philippines and Vietnam, 58 percent of Japanese and 50 percent of South Koreans.

Around 54 percent of Malaysians polled opposed the greater US military commitment to the region, which a majority of Chinese interpreted as an attempt to try limit China's growing power.

But the US still received higher ratings than China in Asia, as well as in Africa, Latin America and Europe.

The US had a 9-point ratings edge over China in Africa and Asia, a 28-point margin in Europe, and a 10-point lead in Latin America.

The converse was true for the Middle East, where China had a far better image, with 52 per cent support, compared to 29 percent favorable for the US.