Muslim Americans reject Islamic extremism by larger margins than do Muslim minorities in Western European countries. However, there is somewhat more acceptance of Islamic extremism in some segments of the U.S. Muslim public than others. Fewer native-born African American Muslims than others completely condemn al Qaeda. (...)
Relatively few Muslim Americans believe the U.S.-led war on terror is a sincere effort to reduce terrorism, and many doubt that Arabs were responsible for the 9/11 attacks. Just 40% of Muslim Americans say groups of Arabs carried out those attacks.

While nearly 80 percent of U.S. Muslims say suicide bombings of civilians to defend Islam cannot be justified, 13 percent say they can be, at least rarely. That sentiment is strongest among those younger than 30. Two percent of them say it can often be justified, 13 percent say sometimes and 11 percent say rarely. (...)
Federal officials have warned that the U.S. must be on guard against homegrown terrorism, as the British suffered with the London transit bombings of 2005. Even so, U.S. Muslims are far less accepting of suicide attacks than Muslims in many other nations. In surveys Pew conducted last year, support in some Muslim countries exceeded 50 percent, while it was considered justifiable by about one in four Muslims in Britain and Spain, and one in three in France.

•  Only 5 percent of U.S. Muslims expressed favorable views of the terrorist group al-Qaida, though about a fourth did not express an opinion.
•  By six to one, they say the U.S. was wrong to invade Iraq, while a third say the same about Afghanistan — far deeper than the opposition expressed by the general U.S. public.
• The survey estimates there are roughly 2.35 million Muslim Americans. It found that among adults, two-thirds are from abroad while a fifth are U.S.-born blacks.

The survey, conducted in December 2006 by the University of Maryland's prestigious Program on International Public Attitudes, shows that only 46 percent of Americans think that "bombing and other attacks intentionally aimed at civilians" are "never justified," while 24 percent believe these attacks are "often or sometimes justified." Contrast those numbers with 2006 polling results from the world's most-populous Muslim countries – Indonesia, Pakistan, Bangladesh, and Nigeria. Terror Free Tomorrow, the organization I lead, found that 74 percent of respondents in Indonesia agreed that terrorist attacks are "never justified"; in Pakistan, that figure was 86 percent; in Bangladesh, 81 percent. Do these findings mean that Americans are closet terrorist sympathizers?

Since the bombing attacks in London last month, a welter of columnists, writers, talking heads and ordinary people have puzzled over the mystery of British Muslims, one in four of whom recently told pollsters that they sympathize with the July 7 suicide bombers. The idea that British Muslims, whose parents received asylum, found jobs, and made lives in Britain, could be so deeply affected by the "oppression" of Muslims in countries they have never visited seems incomprehensible. The notion that events in distant deserts should lead the middle-class inhabitants of London or Leeds to admire terrorists seems inexplicable.
But why should this phenomenon be so incomprehensible or inexplicable, at least to Americans? We did, after all, once tolerate a similar phenomenon ourselves. I am talking about the sympathy for the Irish Republican Army that persisted for decades in some Irish American communities and is only now fading away. Like British Muslim support for Muslim extremist terrorism, Irish American support for Irish terrorism came in many forms. There were Irish Americans who waved the Irish flag once a year on St. Patrick's Day and admired the IRA's cause but felt queasy about the methods.
There were Irish Americans who collected money for Catholic charities in Northern Ireland without condoning the IRA at all. There were also Irish Americans who, while claiming to be "aiding the families of political prisoners," were in fact helping to arm IRA terrorists. Throughout the 1970s, until Prime Minister Margaret Thatcher asked President Ronald Reagan to stop them, they were the IRA's primary source of funding. And even after that they were widely tolerated. I concede there is one major difference: The Irish terrorists were setting off their bombs across the ocean and not in New York or Boston, which somehow made the whole thing seem less real. But in Britain the explosions were real enough. In 1982 -- the year an IRA bomb killed eight people in Hyde Park -- four IRA men were arrested in New York after trying to buy surface-to-air missiles from an FBI agent.