BRUSSELS (Reuters) - President Donald Trump's sharp criticism of NATO has not weakened Europeans' faith in the United States' commitment to defend their countries if attacked by Russia, a Pew Research Center study showed on Tuesday.
Trump, who is the de-facto leader of the Western military alliance, is due to meet NATO leaders in Brussels on Thursday but called the North Atlantic Treaty Organisation "obsolete" during last year's U.S. election campaign.
While he withdrew that charge last month, he has warned allies they must spend more on their security or risk losing U.S. support, appearing to cast doubt on NATO's founding principle that an attack on one ally is an attack on all.
In a Pew survey - taken before Trump changed his stance on NATO on April 12 - European faith in U.S. military support for the alliance was steady among respondents in Britain and Spain, rose in Poland and dipped only slightly in France and Germany.
However, the Pew study found that Europeans are reluctant to come to each other's aid, particularly in Germany, something that is unlikely to reassure U.S. officials who want Europe to do more for its own security.
"Majorities in all the NATO member countries surveyed believe the U.S. would use military force to back up an alliance partner if it got into a serious military conflict with Russia," the study said.
Russia's 2014 annexation of Crimea from Ukraine raised the stakes for NATO, prompting the alliance to send troops to the Baltic states and Poland to reassure governments which fear they could also be subject to a Russian incursion. Moscow denies any such plans.
The Pew study noted that while Germany has the fourth-largest defence budget in NATO, "just 40 percent of Germans believe that Germany should provide military force to defend a NATO ally if it is attacked by Russia".
However, in France, Europe's main military power along with Britain, 53 percent of people surveyed said they supported defending a fellow NATO member, up from 47 percent in 2015.
Trump's "America First" rhetoric, his conflicting signals on Russia and his shifts on NATO have left European governments at a loss over what to make of the new president, despite support from senior officials including Vice President Mike Pence, who visited the European Union and NATO in January.
The study said that while a majority of U.S. citizens support defending other NATO countries, the political backing in the United States for such a move was greater among liberals than among conservatives, many of whom voted for Trump.
"Donald Trump's criticism of NATO resonates with his political base. Less than half of Republicans hold a favourable view of the alliance," the study said.
The survey was conducted among 9,761 respondents in the United States, Canada, France, Germany, the Netherlands, Poland, Spain, Sweden and Britain from Feb. 16 to April 10.
Reporting by Robin Emmott; editing by David Stamp