At the south-east corner of Hyde Park in London, 52 singular columns of stainless steel rise from the ground, a permanent memorial to the victims of the worst terrorist attack in the city's history. Five years ago this week, four British men walked on to London's transport system and, above and below the capital, exploded their backpacks, killing 52 people, injuring hundreds more and ushering in a new era of security restrictions.
Five years on, the situation is getting better, but also worse. This week, British courts convicted three London men for their parts in the 2006 "airline bomb plot", an attempt to bring down transatlantic airliners using liquid explosives. On the same day the men were convicted in London, three Norwegian residents were arrested in connection with a plot to attack targets in Norway. This week too, in the US, prosecutors unveiled charges against four men over a plot to bomb the New York subway system. Two US residents have already pleaded guilty.
The arrests and convictions show the evolving nature of the new threats. Firstly, their connections: although the cases concerned three separate plots, there were clear links within them between Britain, America, Germany, Norway and Pakistan. Secondly - and of more concern - was that nearly all of those involved were "homegrown", involving citizens or residents of the countries they were plotting against.
That is the largest change in the security landscape of the past few years. The men who now plot and carry out Islamist violence are products of their own societies. And they are not necessarily the children of immigrants; in Germany in February, four men, two of them German converts to Islam, were sentenced for their part in a plot to attack German targets, called the "Sauerland group" after the region in western Germany where they were caught. In the United States, a North Carolina resident called Daniel Boyd is awaiting trial, suspected of leading a terror cell composed of mainly white converts to Islam.
Yet while this change has redefined the security landscape, attitudes have not caught up. The mentality of Europe and North America remains locked in the aftermath of the September 11 attacks: looking for groups trained, funded and controlled from abroad. But the era has changed. We are now in the era of the lone wolves. The good news is that intelligence services are getting better at identifying and stopping Islamist plots. Since the 2004 Madrid attacks and the 2005 London attacks, there have been no large scale attacks in the West. In April, Europol, the European Union's police agency, reported a decrease in the number of terrorist attacks on the continent in 2009. Attacks still continue, mainly from separatist and left-wing groups in France and Spain, and deaths still occur, but the trend is downwards.
The bad news is that the number of plots have increased and, on several significant occasions, the public has escaped harm more by luck than design. In New York's Times Square, in London's Haymarket, on Cologne's trains and in the skies above Detroit, deaths were only avoided because the bombs failed to go off as planned. In one sense, homegrown terrorists and plotters ought to be easier to deal with, since they are limited geographically and the state controls the territory. European governments also have experience with domestic terrorism; the UK with Irish republican terrorism, Germany with the Red Army Faction and both Spain and Italy with far-left and separatist terrorism. But the trouble is homegrown plotters are already in the country. Plotters from abroad face an array of immigration and security complications before they even arrive.
One of the benefits of an increased vigilance among Muslim communities in the past few years has been the curtailment of the potential for radicalisation in public spaces such as mosques. But that has brought with it its own challenges. As Muslim communities have distanced themselves from the radical minority in their midst, that minority has become more secretive and introverted. The biggest threats come from those radicalised outside geographical centres and outside traditional terrorist groups - homegrown terrorists and lone actors.
These home and lone actors are the most likely to fall off the radar of the security services. In essence, intelligence agencies and police are chasing ghosts in a vast machine, the few among the many, unsure of which behaviours to suspect and unclear where the next threat will come from. As citizens or residents, these actors are afforded rights - and when governments have tried to limit the rights of the accused, as with lengthy police custody in Spain and lengthy pre-charge detention in Britain, the violations are counterproductive.
Yet while the nature of the threat has evolved, our understanding of it has not. For a start, the idea persists that squeezing Muslim communities harder will filter out suspects. Parts of the political and media spectrum still persist in stigmatising and haranguing Muslim communities, arguing that those communities need to do more. Yet Muslim communities across Europe face the same problems in identifying potential terror suspects as everyone else; if the intelligence services can't pinpoint suspects, it's not clear how the man on the street can. Some sections of the right - and not only the far-right - have taken the chance to blend concerns about immigration with questions about terrorism, complicating the problem.
At the same time, Muslim communities are becoming better at speaking out, at seeking to put their views to the media and to government. There is a greater understanding that this issue isn't going to go away, that law-abiding Muslims in Europe can't simply disregard Islamist violence as a lunatic fringe. Governments, too, have reached out and tried hard to listen. Innovative schemes aimed at countering the effects of radicalisation have been set up in Germany, Britain and Spain. European countries have become better at co-ordinating "soft" policy on immigrant communities.
But the narrative of terrorism has yet to catch up with a mutating reality. The belief persists that it is possible to identify potential terrorists by their speech - that those with left-leaning views on foreign policy or immigration, or devout beliefs, are de facto suspects. In the United States, the Presidentt Barack Obama's administration has accepted what seemed to many observers obvious from the start, that the Bush-era doctrine of an endless "war on terror" was alienating and counterproductive. "Our enemy is not terrorism, because terrorism is but a tactic," said John Brennan, Obama's counterterrorism adviser, outlining America's new national security strategy earlier this year. Part of the strategy focused explicitly on home-grown radicals.
In Europe, the shadow of Iraq is equally long. Those European countries not as involved in the invasion, such as Germany and the Scandinavian countries, felt that they may be exempt. But the new threat touches even them, as the arrests this week show. A change in the narrative matters because it frames the response. Quietly, the intelligence services have spent most of the last decade hunting for the ghosts in the machine. The right narrative helps that hunt by not diverting resources to apparitions.
Faisal al Yafai is a journalist. He received the Ibn Battuta Award for Media in London this spring.