From its style and layout on the page, it appears that the sentence was meant as part of a poem or chant. It's also consistent with how the writer has used poetry in the same letter before. Two Islamists familiar with al Zawahri and al Qaeda's statements also agreed with this explanation and believe it is not contradictory or confusing. Some analysts even suggested the letter may have been meant for Abu Musaab al Suri, also known as Mostafa Setmarian. It is clear through a number of references, however, that the letter was meant for al Zarqawi, who is referred to as the "sheikh of the slaughterers" in the document.
Juan Cole, a professor of history at the University of Michigan, argued on his Web site that some of the language in the letter sounds Shiite. He specifically points out to the greeting at the top "peace and blessings be upon the Messenger of God and his family and his companions" and argues it's more of a Shiite greeting because of the reference to prophet's Mohammed's family. He also points out to references to prophet Mohammed's cousin as "Imam" Ali. Ali is highly regarded by the Shiites, who always refer to him as Imam. His son, al Hussein, is also mentioned in the letter as "Imam" al Hussein.
Serri believes it's not uncommon for Sunnis to refer to Ali and al Hussein as Imams, especially since the reference to Ali comes in the context of "the mausoleum of Imam Ali." As for the greeting at the beginning of the letter, Serri believes it's actually proof that the letter was not written by a Shiite. He argues that Shiites never refer to prophet Mohammed's companions in their greeting, because they stress the importance of his family and were always opposed to the appointment of some of his companions as caliphs following his death.
Stratfor agrees that "referring to Hussain bin Ali as "Imam" is not a Shiite-patented term." "This is a common mistake among those who focus on Sunni (especially Wahhabi) opposition to the Shia -- and assume that Sunnis would not employ language that is more commonly used by the Shia."
Other observations included the writer's references to the date in both Islamic and Gregorian calendars. Some analysts claimed this was uncommon. Two Islamists argued this was not true. Al Qaeda leaders have also often included both dates in publicized statements.
Some analysts argued it was unlikely for al Zawahri to include so much detail about strategy in a letter to al Zarqawi. However, al Zarqawi's letter to Osama bin Laden in February 2004, which was also intercepted by the United States, contained a lot of detail about his strategy. If this is how al Qaeda leaders are communicating, then there is no reason not to include all the details.
Most puzzling, however, was the writer's tone. Al Zawahri seemed extremely careful not to upset al Zarqawi by praising him and stressing numerous times that he knows better because he's in the battlefield. It seemed like a strategy on al Zawahri's part to convince al Zarqawi to change his methods in Iraq. Al Zawahri seems to really believe that Iraq could be the golden opportunity to reach his dream of establishing an Islamic caliphate. He's therefore extremely careful when talking to the one man who he thinks may help him achieve that.
Even though there is no way to determine for sure if the letter is authentic, there is no solid evidence that it is fake either. Islamists and a number of Arab journalists seem to believe that the letter was really written by al Zawahri. Yousri Foda, chief investigative correspondent for al Jazeera TV who covered al Qaeda extensively, also said it fits al Zawahri's style.
Salameh Nematt, the Washington editor of al Hayat newspaper, also thinks the letter is genuine.