The following are excerpts from the forum discussions on the subject:
"With British Troops Murdering Muslims, There Can Be No Covenant of Security in the U.K."
On January 18, 2008, a member of the Al-Ekhlas English forum (www.ek-ls.org ) posted the following inquiry in English: "Can anyone [provide clarification regarding] the covenant of security [i.e. assurance of protection]? In the U.K., there seem to be many opposing views on this subject. On the one hand, some brothers say we must respect the covenant of security because in the U.K. we live among the kuffar [i.e. non-believers] and [therefore] we have a covenant with them. Others say we no longer have a covenant of security because of the arrests, detentions, and charges [against our brothers], and the monitoring of mosques by the British government...
"British foreign policy in Afghanistan and Iraq has caused the murder of women and children. Some brothers have suggested that this also justifies [the revocation of the] covenant of security in the U.K.. Other brothers have said in the forums that if you live outside the U.K., there is no covenant of security and that it [i.e. the U.K.] may be targeted.
"With all the sheikhs arrested or exiled, i.e. Sheikh Abu Hamza, Sheikh Abu Qatada, and Sheikh Omar Bakri, [and] surely with the British troops murdering Muslims, there can be no covenant of security with the U.K..
"Can someone please clarify for me what the correct situation is regarding the covenant of security with the U.K. and with other European countries, as I am very confused?" 
"It Is Best To... Declare that You are At War With the [Non-Believers]"
In response to this query, a forum member cited the full text of a 2003 fatwa by Saudi sheikh and Salafi jihadi scholar Nasser Fahd, which relies on the legal precedent of killing Ka'b Ibn Al-Ashraf  to justify the violation of aman committed by the terrorists who carried out the 9/11 attacks.  The writer expressed his reservations regarding such a justification, saying: "If you look in Sharh as-Siyar al-Kabeer by as-Sarkhasi [a legal book by a Hanafi scholar], you can see numerous examples of the covenant of security that are less obvious than a visa. He [Sarakhsi] says that as long as a Kaafir [i.e. non-believer] thinks he has your assurance of safety, and [if] you did something that normally [conveys such an assurance], this [constitutes] a contract between you and him. I know that you [i.e. the inquirer] did not ask about visas, but I think that being the citizen of a particular country [makes it] even more evident that you are not going to harm that country. In fact, they [i.e. Westerners] view a citizen's betrayal (treason) as the worst possible offense, because they do not expect such an act of a citizen..."
The writer then offers what he views as a legal solution which allows the revocation of aman within the boundaries of Islamic law. He proceeds as follows: "Therefore, in order to stay away from doubtful matters, it is best to simply declare that you are at war with the kuffar before you [commit] any act of jihad on their land. If you are too afraid to make it open... it would be better for you to make hijra [i.e. to migrate] to a land of jihad, where you can openly proclaim that you are at war with Britain or with any other country you choose."
"By Carrying Out Operations on the U.K. Mainland, You Are Retaliating for the Bombing of Our... Country's Infrastructure"
Other forum participants were much more vehement, supporting outright violation of the "assurance of protection" offered to Muslims in the form of a visa or citizenship. As one member phrased it: "The answer is self-evident: As far as I understand, the covenant has ceased to be valid..." Another writer cited legal justification to support this view: "Just bear this in mind: Britain has officially 'declared' war on two Muslim nations and, [consequently], we are in a 'state of war.' Any [preliminary] agreements (including the covenant of security) have now been broken and cannot be reestablished until the 'state of war' is ended.
"British Muslims have an obligation to Iraqi and Afghani Muslims, and that includes assisting them against offenders in every possible way. By carrying out operations on the U.K. mainland, you are retaliating for the bombings of our governmental/financial institutions, military/civil installations. and our country's infrastructure, such as bridges - not forgetting, of course, the thousands of innocent Muslim lives caught up in the bombings. Moreover, [by carrying out operations,] you are pressuring the U.K. government [to stop] its aggression.
"It's a simple formula... the only formula. However, 99% of [the] people, including 'BIG TIME' scholars, just don't want to engage in this struggle, i.e. jihad, [and] they will find many excuses..."
 See, for example, MEMRI Special Dispatch No. 1816, "Participants in Islamist Forums Discuss Proposal for Terrorist Attack in Paris," January 18, 2008, http://memriiwmp.org/content/en/report.htm?report=2516.
 For a classical discussion regarding the restrictions imposed on a Muslim who enters a non-Muslim country with aman (assurance of protection), see Ibn Qudama, al-Mughni (Riyadh, 1997), v.13, pp. 52ff. For a more modern discussion of this notion, see e.g. Abu Basir Al-Tartousi's response to the question of whether Muslims are allowed to steal or to harm unbelievers' property when they enter the unbelievers' country with an assurance of protection: http://www.altartosi.com/book/book03/index.html.
 According to Islamic tradition, Ka'b Ibn Al-Ashraf, who was a member of the Jewish tribe Banu Nadir in Medina, incited the Meccans against the Prophet. The Prophet ordered him killed, and, according to one tradition, the Prophet's companions provided Ka'b with a false aman in order to gain his trust, and then used it to lure him out of his house at night and kill him.