Abu Musab al-Suri, a modern jihad "theorist" for Al Qaeda, who is believed to have been involved with both the Madrid (2004) and London bombings (2006), and perhaps even an attack on the Paris metro in 1995, was reported to have been released from Syrian captivity in February 2012. After being captured by the CIA in 2005 Al-Suri had been transported to the country of his birth, Syria, and held there for 6-years. According to a February 4, 20012 report in The Telegraph of London,  by Jason Lewis,

...he [al-Suri] is now said to have been released as a warning to the US and Britain about the consequences of turning their backs on President al-Assad's regime as it tries to contain the uprising in the country.

The May 2012 edition of Al-Qaeda's English language screed "Inspire," contains an essay claimed to have been penned by al-Suri entitled,  "The Jihadi Experiences--The most important enemy targets aimed at by the individual jihad."

Al-Suri's alleged essay opens by proclaiming the overarching, murderous goal--to be accomplished by jihad terror:

The goal of the operations of the Resistance and the Individual Terrorism Jihad is to inflict as many human and material losses as possible upon the interests of America and her allies

He instructs local American jihadists to strike "in the heart of America," for pragmatic reasons, with additional advice regarding especially vulnerable targets:

[p. 23] The fundament for the operational activity is that the mujahid, the member of the Resistance, practices individual jihad on his land, where he lives and resides, without the jihad costing him the hardship of traveling, migrating, and moving to where direct jihad is possible. The enemy today is one, and he is spread everywhere, alhamdullilah.

[p. 24] ...The type of attack, which repels states and topples governments, is mass slaughter of the population. This is done by targeting human crowds in order to inflict maximum human losses. This is very easy since there are numerous such targets such as crowded sports arenas, annual social events, large international exhibitions, crowded marketplaces, sky-scrapers, crowded buildings... etc.

Subsequently, in the Winter 2013 issue of Inspire, al-Suri (in an ostensible follow-up diatribe) invokes the classical Koranic verse of jihad terror--and Muslim Brotherhood's emblematic credo--Koran 8:60 (Against them make ready your strength to the utmost of your power, including steeds of war, to strike terror into (the hearts of) the enemies, of God and your enemies") to employ mass murderous jihad attacks as a "deterrent" which  

...reach[es] into the homes of the American invaders and their allies of infidels from every nationality and in every place.