Well aware that Mr. Obama shuns the term “Islamist extremists,” the Conservative British prime minister reacted strongly at the meeting when the president, who chaired the session, advised the assembled foreign leaders to avoid profiling Muslims because “violent extremism is not unique to any one faith.”

“Barack, you said it and you’re right — every religion has its extremists,” Mr. Cameron said. “But we have to be frank that the biggest problem we have today is the Islamist extremist violence that has given birth to ISIL, to al-Shabab, to al-Nusra, al Qaeda and so many other groups.”

Cameron also addressed ways to counter extremism in Western countries.

My point is simply this: we have to stop this process at the start, not at the end. So of course we have to win militarily; we have to have the political solution; we need all the propaganda I’ve spoken about – but we also need to challenge the extremist world view right at the very start.

What does that mean? Well, in Western countries, it means that we have to root out the extremist preachers that are poisoning the minds of young Muslims in our country. We have to build more integrated societies so that young people feel they truly belong.

We need to make sure we don’t allow the incubation of an extremist world view even before it gets to justifying violence. We’ve got to get it out of our schools, get it out of our prisons, get it out of our universities. I believe in freedom of speech, but freedom to hate is not the same thing.

At the end of the meeting, Obama conceded that Cameron made good points, but did not address his implicit rebuke. “I thought David Cameron’s point was excellent, that we are focused on violent extremism, but violent extremism is emerging out of an extremist worldview that has to be counteracted,” the president said.