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Are 'lone wolf' attacks the new path to terror?

Justin Tallis / AFP - Getty Images

A woman reacts as she looks at floral tributes left at the scene where Lee Rigby was killed outside Woolwich Barracks in London on May 24.

LONDON – The horrific public slaying of a soldier in London, five weeks after the Boston Marathon bombings, illustrates the possible emergence of a new terror trend towards unsophisticated attacks that are practically impossible to prevent, intelligence experts warned.

Lee Rigby, a 25-year-old father who had served in Afghanistan, was killed in broad daylight Wednesday as he walked near an army barracks in Woolwich, southeast London.

Eyewitness reports suggest the killing was ideologically motivated, carried out in protest at British military actions in Muslim countries, based on what the alleged attackers were heard to say.

And although London is no stranger to terrorism – dozens of civilians and soldiers have been killed by Irish republican bomb blasts over the past four decades – it is still coming to terms with the latest threat: isolated, uncoordinated attacks.

“I think what we've seen in London, and Boston previously, is largely the new face of al Qaeda-inspired attacks,” said NBC News counter-terrorism analyst, Michael Leiter.

“These are no longer the large scale sophisticated plots from overseas but instead very unsophisticated and simple attacks which can still very much affect the psyche of cities.”

Most chillingly, Leiter believes such actions by “lone wolves” are harder to thwart than planned attacks directed by overseas terror organizations whose activities are monitored by intelligence agencies.

“These are some of the most difficult attacks to stop,” he said. “In London and the United Kingdom you have incredibly capable security forces; but when two individuals do this with potentially no other connections, to stop them when they're using things like knives and cleavers makes this almost impossible to stop beforehand.”

Rebecca Rigby, the widow of the British soldier who was murdered in London, fights back tears to talk about the "devoted father" she never expected to die while on UK soil. "You think they're safe," she says alongside their family spokesman.

Underlining his point, security sources say both the suspects in this week’s attack were known to intelligence agencies. It is not known if they were deemed to be a low risk.

A key similarity between this week’s attack and the Boston bombings was the possibility that the suspected perpetrators picked up their techniques from al Qaeda publications on the Internet, according to Ed Campbell, home affairs editor at NBC’s U.K. partner ITV News, which obtained exclusive pictures of the aftermath of the attack.

“Its emphasis is on DIY attacks which involve low-tech methods and no contact with an al Qaeda hierarchy because that gives the security forces a lead,” said Campbell.

The machete killing was not the very first incident of its kind. In 2010, a young Bangladeshi Muslim, Roshonara Choudhry, tried to stab a London lawmaker to death with a knife to avenge his support for the war in Iraq. She was jailed for life.

And in 2008, four British Muslims admitted their role in a plot to kidnap and behead a British soldier, and record the execution on camera for use as jihadist propaganda.

Raffaello Pantucci, Senior Research Fellow at the Royal United Services Institute think tank, said Wednesday’s attack displayed “a level of brutality, I think, we haven’t seen quite yet.”

 “It certainly looks like a terror incident of a trend we have increasing seen recently - small groups of individuals who decide to carry out actions for their own reasons… who decide to choose their targets.”

The two suspects, aged 22 and 28, are under guard in hospitals after being shot and arrested by police following the murder of Rigby on Wednesday in broad daylight. They have not yet been charged.

There have been two more arrests in the murder of a British soldier, who was stabbed and hacked to death on a London street. The uncomplicated, simple attack has altered London's psyche. NBC's Michelle Kosinski reports.

Detectives were also questioning another man and a woman, arrested on Thursday on suspicion of conspiracy to murder, as they tried to determine whether those responsible had links to militants in Britain or overseas.

"This is a large, complex and fast-moving investigation which continues to develop," police said in a statement, Friday. "Many lines of inquiry are being followed by detectives, and the investigation is progressing well.”

What is not yet clear is how and where the London suspects were radicalized. Although media reports in London said the two were of Nigerian descent, it is not known if there is any link to the Islamic terror groups that have plagued Nigeria in recent years.

The FBI is investigating whether one of the Boston bomb suspects was radicalized during a 2012 trip to his homeland, the Russian republic of Dagestan.

Dzhokhar Tsarnaev, 19, is charged with using a weapon of mass destruction for the April 15 bombing that killed three and wounded 176 in Boston and could face the death penalty.

The suspect's older brother and accused accomplice, Tamerlan Tsarnaev, 26, was killed in a firefight with police, and investigators are trying to determine if anyone else was involved.