The killing of Drummer Lee Rigby in Woolwich has reopened the debate about those who carry out acts of violence in the name of Islamist fundamentalism.
Experts give their opinions on how society and the authorities should react to this incident and what could be done to combat radicalisation in the UK.
Dr Brooke Rogers, senior lecturer at King's College London
Some members of the public may hear about extremist acts and want to do something about radicalisation - and they can.
People can engage in volunteering and mentoring schemes, get employment in a non-governmental organisation. They can help make vulnerable individuals become part of a group.
But we do not do enough to encourage critical thinking in young people. Many undergraduate students are very good at regurgitating information, but in terms of challenging an argument, or knowing where to look for information to make a challenge, we are lacking.
So if you give young people the critical thinking skills in the first place, they will be less vulnerable to extreme views - whether that is Islam, gangs or drugs.
The problem in the UK is with the way that children are being educated.
We also need to build relationships with communities, not just Muslim ones, make them feel comfortable so that if they have concerns, they can have a quiet word without finding armed police breaking down their neighbours' doors.
There should be a multi-agency response that includes community leaders, as we've seen elsewhere in Europe.
I am very uneasy about how the government has cut funding for the Prevent scheme, which tackles extremist ideology.
We need to reinvest in it and it's about putting people back into communities, it's not just about technology and spying.
Bob Stewart, Conservative MP for Beckenham
Terrorists, in particular those who say they are Islamic fundamentalists, always say they are at war with us. We are silly if we do not accept that is the way they will operate - as though they are at war.
We need to revise the European Convention on Human Rights so that the European Court of Human Rights does not determine whether we can expel preachers who are preaching hate.
We need a British Bill of Rights so our courts can say "this person should not be on our soil" and send them out of the country.
We also need the draft Communications Data Bill to be fast-tracked into law as well, to give the security services the tools they need to deal with this threat.
I would like to see universities ban meetings that don't allow women to attend, don't allow certain races or types of person, or advertise as being anti our society.
And the vast majority of the Muslims in this country are against violence, so it's time for them to prove they really are against it.
Why don't they have a rally against terrorism in Trafalgar Square, which would also help ease some of the tensions against them and may stop the hate crimes like the ridiculous attacks on mosques?
There should be a mass Muslim rally and they should stand up and say these terrorist acts are "not in my name".
Khalid Mahmood, Labour MP for Birmingham Perry Barr
Intolerance and hatred have been brewing in this country since the 1980s when we tacitly accepted the presence of extremist preachers such as Abu Hamza and Omar Bakri Muhammad.
Our own belief in freedom of speech, and the government's preoccupation with the Cold War, gave them space to preach and recruit.
At dozens of colleges and universities they targeted young men and women who had become alienated from their own communities.
Often second-generation immigrants, these individuals were easy targets as they struggled to reconcile their faith and life in a secular society.
They were rich pickings for these preachers with their message of moral absolutism and radical anti-imperialism. Organisations such as Hizb ut-Tahrir became fashionable in the 1990s and, while not as extremist as some, acted as a bridge towards more radical elements.
We need grassroots change in the community. The lesson we must learn is that if we tolerate extremist preaching on issues such as women's rights and homosexuality then it very quickly turns to extremist preaching directed at the West in general.
Increasing numbers of young people are being persuaded towards an extremist outlook but they do not necessarily become parts of formal organisations. These groups meet informally and many follow international figures through the internet.
While this problem has to be addressed by the Muslim community, government has a role to play and occasionally this has to be done by the security services - meaning that we should pass the Data Communications Bill into law.
Reyhana Patel, journalist and writer
The media don't help the situation. If you look at how they covered the aftermath of the Woolwich attack, they were demonising Muslims and were Islamaphobic.
Muslim communities in Britain want consistency in the media coverage. There are children being killed by Western soldiers in Afghanistan and there is little or no coverage about that. It makes people feel angry. There's no avenue for them to act in a democratic way, because the government doesn't listen to Muslim communities.
This could lead vulnerable people into radicalisation. It's not the only avenue, but it's a danger for some.
The government's Prevent policy to tackle extremism was rushed through after 7/7 and it has proved to be ineffective in combating home-grown terrorism at the community level.
They need to tackle the root causes of radicalisation in communities through more community cohesion, employment opportunities and a way out of the communities people are trapped in.
There also needs to be a lot more interaction between Muslim and non-Muslim communities through more education and awareness.
There are extremist voices on both sides, and they're the ones getting heard in the media.
There's no middle ground. The real voices aren't coming out and that's what needs to be tackled.
Ross Frenett, Institute for Strategic Dialogue
In the aftermath of the Woolwich attack it is understandable that the government wishes to be seen to "do something" about extremist content on the internet. But this reaction must go beyond simply removing content.
Every minute more than 570 new websites are created, Facebook users share 600,000+ pieces of content and more than 48 hours of content are uploaded to YouTube.
In this environment it is impossible to take down all extremist content: the second that some is removed, it simply springs up somewhere else.
While there may be a limited role for takedowns, the government should instead focus its attention on assisting credible messengers in creating content to counter the extremist messages.
A focus needs to be placed on locating and increase the skills of those messengers who are most credible: former extremists, community leaders and survivors of violent extremism.
Government should aim to work with credible messengers such as our network, together with private sector expertise, and provide training and support for the creation of compelling counter-narratives that can be carefully targeted to ensure these messages reach the right audience: those reading and interacting on extremist forums, websites and social media sites.
Unless we see an increased focus on the creation of positive counter-messages to engage directly with extremist narratives online, the government will find itself in a largely fruitless game of extremist Whack-a-mole, expending a lot of effort with little to show.
Farooq Murad, secretary-general, Muslim Council of Britain
The reaction to Drummer Lee Rigby's murder gives us an indication of how we combat extremism in this country.
We have seen reprisals: mosques attacked, people abused and hateful messages in our mailboxes and on social media walls. But we have also seen examples of partnership and solidarity.
The biggest repudiation of extremism came in the expression of solidarity across all parts of our society: this was symbolised so poignantly when the Archbishop of Canterbury stood in solidarity with Muslims to condemn the murder. It was also seen when the York Mosque defused tensions by inviting protesters from the English Defence League inside for tea.
Engagement and participation are key, not isolation and exclusion. Muslim communities and institutions have examples here to encourage young people away from the allure of extremism.
We must be vigilant and ensure we do not inadvertently give into the demands of all extremists: making our society less free, divided and suspicious of each other.
We do not need policies based on dogma and ideology rather than evidence and analysis.
For example, terms such as Islamism, radicalisation and extremism all have been used in a confusing manner, serving agendas other than countering terror.
Sometimes they have been conflated with conservatism, orthodox practices or even opposing political views on foreign policy.
This means targeting the wrong people, creating unnecessary fear, suspicion and further disengagement. The net result is that more people are marginalised from the mainstream and pushed into dark alleys to become easy prey for extremism, crimes and gang culture.
No doubt our mosques and religious institutions have a role to play. So have our community leaders and organisations.
But they have to be credited for the wonderful work they do, and engaged as equal partners. In brief, we need objective and evidence-based strategies involving all stakeholders.
Raffaello Pantucci, senior research fellow at the RUSI think tank
Radicalisation is defined in the government's Prevent strategy as "the process by which a person comes to support terrorism and forms of extremism leading to terrorism".
It is a social process but also a deeply personal experience. The pathway by which one person is radicalised can have a completely different effect on someone else. This makes it very difficult to devise a one-size-fits-all answer to the problem. Instead, a menu of tools is necessary to address different causes.
Countering influences online and offline is harder than it might sound. Simply shutting down websites and arresting individuals do not necessarily eliminate the problem.
On the contrary, such moves can drive people underground, making them potentially more appealing and attractive, or they will simply adapt to be on the right side of any ban.
This is not just a law enforcement issue. As a society we need to counter the all-encompassing narrative that states that the West is at war with Islam. This is a message that should be repeatedly rejected at every level: politician, community worker, citizen.
Coupled with this, our societies should engage in practices that highlight how open and free we are, and hold power to account when mistakes are made.
The sad truth, however, is that certain decisions that are made will be interpreted by extremists as something that supports their worldview. Very little will be ultimately possible to persuade them otherwise.
The answer is to recognise and acknowledge where we make mistakes and realise that society will always have its discontents.
Dilwar Hussain, president of the Islamic Society of Britain
It is vital to tackle extremism. This is a serious problem that threatens our society, as well as the future of the Muslim community here.
People may often say that extremism and radical Muslim views are there because of a number of reasons, including conflicts that our country is involved in abroad and the discrimination that Muslims face at home.
As much as these issues are serious and need resolution, they can never be an excuse or grounds for terrorism.
Tackling extremism is a difficult and serious task and we all have some role to play in that.
Muslim leaders, preachers and teachers cannot become police or intelligence officers. The relevant agencies have to do their job in the way that they know best. But Muslim communities can play an important role.
They can give a clear signal of what Muslims actually stand for - peace - and what they will not have any time for - violence and terror.
But Muslims also need to think hard, as many are doing, about what our faith means to us today and how we can live that best in the context of modern Britain.
That is a concern that goes far beyond just tackling extremism, but it will have a profound impact on those that feel so disconnected from society, in the name of a medieval reading of Islam, that they can wreak violence on their own home and their own people.
Pete Mercer, vice-president (welfare) at the National Union of Students
One of the suspects in the terrible events in Woolwich last week was a university student eight years ago.
However, there has been little evidence so far that this has any link to his radicalisation.
Even so, universities are acutely conscious of their responsibilities and the institution concerned is carrying out a full investigation.
The higher education sector has a difficult balancing act. Universities are required by the Education Act 1986 to promote freedom of speech, but there are also duties to protect students from harm, including speakers who incite violence and extremism.
Identifying those speakers is rarely as clear-cut as some critics like to pretend: messages may be subtle, backgrounds unclear.
The NUS and students' unions play their part, working with detailed guidance to assess risks and, if necessary, stop events.
Both NUS and many unions have "no platform" policies that specifically ban certain extremist organisations from speaking at official union events - including, let's not forget, right-wing extremists such as the BNP.
There is a clear need for all in society to respond in the right way. The sharp rise in alleged hate crimes against Muslims and mosques since last week is deeply worrying. Politicians, the media and commentators must be responsible in their public pronouncements.
A panicked crackdown would be counter-productive, fuelling exactly the disaffection that makes some so vulnerable to messages of hate. A considered approach is critical.
Nicola Dandridge, chief executive of Universities UK
Universities have been engaged in tackling radicalisation for a number of years and Universities UK issued updated guidance to all universities in 2011.
We also launched a new website this month to help universities deal with the challenges of tackling violent extremism, as part of their broader responsibilities to students and staff.
Universities have engaged extensively with the government's Prevent strategy and there has been good liaison with the police and security services. We have to remain vigilant and ensure that any illegal activity on campus is reported to the authorities.
One difficult area for universities is handling campus meetings involving controversial speakers.
While universities have a duty to be places where difficult and controversial areas are discussed, there are limits, and they draw the line at speakers who break, or are likely to break, the law.
Many universities have developed specific protocols for managing speaker meetings, which are being shared to help all institutions manage this challenging area.
Universities are not closed communities and students have many different influences on them, including the internet, religious institutions and organisations and groups off campus. Universities are only part of their lives. This is an issue for society as a whole.