Intelligence experts have given a mixed response to a new report on the 7 July attacks that found a lack of resources meant the bombers were not intercepted.
The Commons Intelligence and Security Committee report lacks "penetrating criticism", according to Crispin Black.
But Glenmore Trenear-Harvey said the report reflects the difficulty involved in monitoring potential attackers.
The report said two of the bombers were known to security officers, but the threat they posed was not realised.
The MPs' report said the security services had come across 30-year-old Mohammad Sidique Khan and fellow bomber Shezhad Tanweer, 22, while they were investigating other cases.
Operatives knew the pair had travelled to Pakistan and it was "likely that they had some contact with al-Qaeda figures", according to the committee.
The cross-party group of MPs said intelligence officers had "more pressing priorities" at the time, including the need to disrupt known plans to attack the UK.
"It is important to understand more about the process of radicalisation and how you can prevent people from being led into the arms of extremists"
The failure to intercept the bombers was largely due to a lack of resources in the intelligence services, the report concluded.
This finding prompted criticism from intelligence analyst Crispin Black, the former adviser to the government's Joint Intelligence Committee.
"Its principle conclusion seems to be that there was a lack of resources," he said.
"It does not even seem to deign to investigate why there was a lack of resources four years after 9/11, and two years after the entry of the war in Iraq."
US inspiration
Comparing the report to the inquiry into the 11 September 2001 attacks in the US, Mr Black said it had been a "limp effort" which lacked "penetrating criticism".
"I think we need to look for inspiration and example to the US," he said.
"When 9/11 happened to them they went for it. They searched their hearts, they left no stone unturned. The calls for a more 9/11 attitude to 7/7, I think, will increase.
"No-one is suggesting that... [they were]... biased, all that people are suggesting is that it hasn't got the full story and hasn't been punchy enough in the criticism it has made."
But Prof Paul Wilkinson, who chairs the Centre for the Study of Terrorism and Political Violence at the University of St Andrews, said such a comparison was unfair.
"The 9/11 Commission was set up as a much more comprehensive inquiry.
"What more do you want in the counter-terrorist world - to have two of the people that then carry out the biggest terrorist attack in London on your radar"
"This report is a much more limited affair. Of course it is not the equivalent of a public inquiry - it isn't fair to compare them.
"Of course there would be a lot of support for a public inquiry... I certainly can understand why there is that feeling."
Mr Black also highlighted the fact that two of the bombers had been known to security officers.
"What more do you want in the counter-terrorist world? To have two of the people that then carry out the biggest terrorist attack in London on your radar - not just once, but again and again.
"That was a big, major intelligence blunder and we need to look at how to put that right."
Mr Black suggested the report was not as critical as it could have been because "largely what you will see is more or less what they [MPs] would have been told by the intelligence services - perhaps with some milder and sometimes more reasonable criticism put into it".
Glenmore Trenear-Harvey suggested the report's conclusions were correct and, ultimately, the intelligence services were not culpable in any way regarding the 7 July attacks.
He said the report exposed the "sheer volume of terrorist threats" faced by the UK, pointing out that nearly 1,000 individuals in the country are identified as having a "potential terrorist impact on us".
The security analyst said round-the-clock surveillance is "hugely demanding of resources" , pointing out that it can take up to 50 people with surveillance training to maintain 24-hour surveillance on one person.
"If we had a thousand potential terrorists, we would need 50,000 trained officers," he said.
"The security services, specifically MI5, have increased since 11 September 2001, but they have only gone up to 2,600 people from a base of 2,000, so there is a problem."
Resource problems
The report said the "radicalisation of British citizens" was still not fully understood or properly taken into consideration by the intelligence community.
And MPs expressed concern that more was not done sooner to tackle the development of "the home-grown threat".
Prof Wilkinson echoed these sentiments, although he suggested these themes could have been taken further.
He told BBC News: "It is important to understand more about the process of radicalisation and how you can prevent people from being led into the arms of extremists."
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