The Secret Organization of al-Qaeda in Europe claimed responsibility for the July 2005 London subway bombings, although it remains unclear whether they actually committed the attacks.  Little is known about the group's size and structure, capabilities or leadership, which fosters the possibility that they may not be a legitimate organization at all.  However, the group may consist of al-Qaeda-inspired individuals who have no direct ties to the organization, or a wing or an alias of a wing of al-Qaeda. <P><br />On July 7, 2005, four suicide bombers coordinated an attack targeting the London public transit system. Bombs exploded on three subway trains and one double-decker bus, killing 53 people. <P><br />On the day of the attack, a claim was made on a well-known Islamist website forum, Al-Qal3ah or "the castle." The claim stated that the attack had been carried out in retaliation for the "massacres" committed by British forces in Iraq and Afghanistan and warned of attacks against other countries, specifically Denmark and Italy, who also had troops fighting in those regions.  Due to an error in one of the quoted Koran verses and the fact that the claim has never been independently verified, it is widely believed to be a hoax. <P><br />Speculation as to the nature and legitimacy of the Secret Organization of al-Qaeda in Europe continues. It remains unclear how the four London suicide bombers are connected to the group, if at all. Two of the bombers are known to have visited Pakistan and studied at Islamic learning centers. In a video released a year after the attack, al-Qaeda deputy Ayman al-Zawahiri claimed the two men had trained at al-Qaeda camps; however, their presence at the training camps has never been verified. <P><br />The Secret Organization of al-Qaeda in Europe was not the only group to claim responsibility for the London bombings. On July 9, 2005, the Abu Hafs al-Masri Brigade also issued a statement claiming responsibility. The al-Masri Brigade is closely linked to al-Qaeda, though it is not clear if it is simply the European division of al-Qaeda or an alias for another existing organization. The Brigade has issued false claims of responsibility for previous events including the 2004 Madrid bombings and the summer 2003 blackouts in North America. On September 1, 2005, al-Qaeda released a video showing the London bombing mastermind, Muhammad Sadiq Khan, and al-Zawahiri separately addressing the London attack. The video was edited to suggest a direct link between the two men, but there is no indication that they had ever met or communicated. Many took the video as proof that al-Qaeda was responsible for the attack while others saw it as merely an endorsement of the attack. <br />