Tunisia attack proves we cannot stop terrorists carrying out operations against Britons in Muslim countries

At home, the police and MI5 have been much more effective, disrupting 40 terror plots in the 10 years since 7/7 and four in the past year alone

A police officer carries a casualty to safety (Reuters)

David Cameron’s promise of a “full spectrum” response to the indiscriminate murder brought by Islamist terrorism has done nothing to reduce the risk of further attacks.

The horrific events in Tunisia proved what our counter-terrorism chiefs have known for some time: we cannot stop terrorists carrying out operations in Muslim countries with established terror networks.

At home, the police and MI5 have been much more effective, disrupting 40 terror plots in the 10 years since 7/7 and four in the past year alone. But the security threat level remains at “severe”, which means an attack on the UK is still “highly likely”.

“Operation Strong Tower” terror training exercise in London, conducted on 30 June and 1 July, demonstrates how much this threat has evolved since the 9/11 attacks. Security advisers have to plan for possible assaults from the sky, on our underground transport systems and now the increasingly likely Mumbai-style operation in which determined gunmen attempt to massacre the civilian population and expect to die in the process.

The SAS has long prepared to combat this kind of terror scenario on the streets of London. Now reports suggest that the Metropolitan Police has trained its own special forces unit. Our other cities must make sure that they, too, are properly prepared for this kind of roving terrorism.

What the security agencies fear most is a home-grown attack carried out by an extremist with no previous record radicalised on the internet.

Armed police and soldiers are a very reassuring presence on British streets but they can play no role in the battle of ideologies. It is in this realm of the “existential” conflict that Isis excels, combining an unmatched command of social media with a powerful message that promises an authentic Islamic life in the “caliphate”.

Since the US-led coalition began its bombing campaign against the group last year, the militants have increased the territory they hold. At the same time up to 2,000 British citizens may have gone to join the fighting. And barely a week goes by without a family reporting a relative setting out for Syria, Iraq or Somalia.

The failure to win this war of ideologies is partly reflected by the ratcheting up of the political language. At the same time the Government is unveiling controversial policies to beef up the so called “snooper’s charter” and place a duty on nursery school teachers to report signs of radicalisation among children.

The macho language and get-tough policies are counter-productive and will achieve only one thing – the alienation of the very community the Government says is crucial to beating the ideologies of hate and terrorism.

Operation Strong Tower will help the police and emergency services prepare for a terrorist attack – but it won’t do anything to stop someone from deciding to launch an attack in the first place.