Al-Qaeda’s peculiar constitution as an organization and its proven ability to plan and execute mega-terror attacks makes it the most likely candidate to pull off the world’s first serious terrorist attack involving weapons of mass destruction.  Al-Qaeda’s attempt to cause massive destruction would serve all the traditional purposes of terrorism: symbolism, propaganda and psychological impact, irrespective of the failure or success of the mission. Precisely because of pervasive speculation surrounding WMD terrorism, it would be more surprising if terrorists didn’t try to acquire these weapons. While it is generally agreed that a mass-casualty terrorist attack involving WMD is inevitable, the precise timing of the assault depends on the dynamics determining the balance between motivation and capabilities.
Weapons of mass destruction – biological, chemical, radiological and nuclear weapons – are not easy tools to handle. Consequently there have only been two cases of attacks involving WMD: the Aum Shinrikyo case in Tokyo in 1995, and the anthrax letters in the United States in the fall of 2001. These basic and crude attacks neither resulted in mass casualties nor had a massive political impact. A successful attack causing mass casualties and generating catastrophic political and social instability is dependent on acquiring high technical expertise and having the motive and capability to destroy masses of civilians and possibly obliterating entire human communities. There is little doubt that al-Qaeda qualifies for the latter requirement, but its ability to acquire in-depth technical expertise is much in doubt, not least because for now at least the organization is on the defensive.
The most suitable weapon of mass destruction for terrorist purposes would be biological, radiological or chemical. Nuclear weapons are more difficult to develop, or to obtain by buying. In March 2005, a jihadist forum al-Ma’sada published a-do-it-yourself plan to make a dirty bomb.  This is an indicator that the broader Salafi-Jihadist tendency that takes inspiration from al-Qaeda’s ideological and methodological example is exhorting jihadists everywhere to endeavor to develop WMD. But given the sheer complexity of developing or acquiring WMD and then successfully deploying it against suitable targets, it is unlikely that freelance jihadists or even associated organizations will be able to execute a WMD attack. The attack will likely be carried out by the hardcore of al-Qaeda for primarily two reasons: firstly the network has nearly 15 years experience of being at the cutting edge of terrorism and secondly it alone has access to the most competent and accomplished human resources.
Nuclear or radiological weapons don’t have the same fear-effect as biological and or chemical weapons. Moreover chemical weapons are easier to produce than biological weapons, but their capacity to cause mass-casualties is much smaller. A biological weapon would be the best choice for al-Qaeda, considering its potential to cause mass casualties and spread infectious over vast distances.
The employment of mass-casualty terrorism conforms to the agenda and worldview of the increasingly rootless global Jihadism theorized by the al-Qaeda ideologue, Dr. Ayman al-Zawahiri. A few decades ago the main purposes of terrorists were to gain attention and propagandize, while causing mass destruction was simply not an option. In the worldview of rootless Jihadists however, the audience is now superfluous; what matters is to cause mass casualties and create the greatest amount of instability possible, irrespective of the consequences . In this context discussions about motives to deploy WMD are irrelevant. No matter how complex the deep principles or incentives behind WMD terrorism, the only reliable motive is an unflinching desire to slay blindly.
Motivations and capabilities: Present imbalance
The most important capabilities of terrorist groups could be divided into three parts: financial, technological and psychological. Al-Qaeda’s liquidity situation is thought to be favorable, not least because the network continues to receive funding from various sources.  A successful WMD attack would also require enormous technological resources. Globalization facilitates access to advanced technologies in a dualistic way: both terrorists and counter-terrorism agents benefit from this. Psychological capability is the third prerequisite for a successful attack and at the same time, a compulsory quality for terrorists. In the case of WMD terrorism, psychological incentives have to be immense.
Given the difficulty of developing WMD, al-Qaeda may opt to buy these weapons from rogue arms merchants or other criminal networks. But even in the event of acquiring these weapons, their successful dispersion requires sophisticated technical capabilities. In the case of biological or chemical weapons, a small blush of wind or other disturbing factor can destroy the whole project.
Al-Qaeda & WMD
Although Al-Qaeda clearly has an interests in WMD, the group hasn’t directly threatened a WMD attack. The first Islamist ruling about the use of WMD was published in May 21, 2003 by the Saudi Sheikh Naser bin Hamad al-Fahd.  Al-Fahd is one of the young leading Salafi clerics of the Saudi Islamist opposition who supports the culture of global jihad led by Osama Bin Laden.
There has been at least one relatively well documented case of an al-Qaeda directed and funded plot to attack the U.S. homeland with a “dirty” bomb. The plot revolved around Jose Padilla (also known as Abdullah al-Muhajir), a U.S. citizen of Puerto Rican origin, who was detained by U.S. federal agents at Chicago’s O’Hare airport in May 2002. Padilla was allegedly flying into Chicago from Pakistan to conduct a reconnaissance mission on behalf of his al-Qaeda task-masters in Karachi. Much confusion surrounds the Padilla case, but it has been repeatedly claimed that the mission had been originally commissioned by Abu Zubaydah, al-Qaeda’s former senior operational planner, who was arrested in March 2002. It is unclear if information gleaned from Abu Zubaydah’s interrogation directly led to the abrupt disruption of Padilla’s mission.
Currently the central question revolves around the operational viability of al-Qaeda after the consistent and catastrophic setbacks the organization has had to contend with since late 2001. While the long silence since the mega-terror attacks of 9/11 have been interpreted in the context of al-Qaeda’s possible operational demise, it is worthwhile to remember that al-Qaeda follows a logic of its own and is not influenced by any particular audience, let alone a western one. Moreover, the recent video and audio messages of Bin Laden could be interpreted as completing a WMD warning cycle. In other words, al-Qaeda is giving the West a final chance to correct its behavior in the Muslim world before it launches a catastrophic attack.
In recent months much speculation has surrounded the nature of the relationship between Abu Musab al-Zarqawi’s insurgent organization in Iraq and the hardcore of al-Qaeda. Besides his now legendary exploits in Iraq, Zarqawi has been accused of organizing a failed millennium attack in Amman, organizing the assassination of the American diplomat Lawrence Foley in October 2002 and masterminding a foiled plot to attack the headquarters of the Jordanian intelligence service with crude chemical weapons.  If Zarqawi survives the Iraqi insurgency, he may be a likely candidate to lead an al-Qaeda backed WMD attack on the United States homeland or on U.S. interests in different parts of the world. There are two reasons to be fearful: firstly Zarqawi, despite all the legend and misinformation that surrounds him, has proven himself an extraordinarily accomplished and resourceful terrorist; secondly the Zarqawi organization is now staffed mainly by local Iraqis who have more reason than most Islamists to hate the United States. Indeed the radicalizing experience of the Iraq conflict and the fact that a substantial element in Iraq’s Arab Sunni community harbors revenge against the United States for the humiliation which they believe has been inflicted on their country, may lead some Iraqis to take drastic action against their tormentors. While it may only be a matter of time before radicalized and revenge-seeking Iraqis attack U.S. interests outside of Iraq, the real potential for a catastrophic WMD attack planned and executed by this constituency is a sobering thought indeed.
There is already some reports that Iraqis have begun to deploy crude WMD weapons against U.S. forces in Iraq. In the beginning of 2005, the Iraqi correspondent of Mafkarat al-Islam reported that fighters fired mortar rounds containing chemical substances at the U.S. al-Habbaniyah base.  There has also been speculation that Iraqi guerrillas fired rockets loaded with Sarin gas at a US base near Falluja in February 2005.  While neither of these reports have been confirmed, there can be little doubt that Iraq is still a repository of some WMD material, despite the fact that none have been found since the ouster of Saddam Hussein. In an ironic twist of catastrophic proportions the U.S. invasion and occupation of Iraq may result in exactly the kind of attack that it was purportedly designed to prevent in the first place; namely a WMD attack on U.S. interests by Iraqis.
New threats by rootless jihadis to attack Western interests are appearing on jihadist forums more frequently than ever. For instance, in April 2005 the Jihadist website La Voix des Opprimés (the Voice of the Oppressed) published a direct warning to Americans, Europeans, Russians and “other Westerners,” threatening them with biological or chemical attacks.  These warnings may be dismissed as the helpless rantings of armchair mujahideen, but there is little doubting the overwhelming desire of committed Jihadists to acquire and deploy weapons of mass destruction against western targets. Currently the disconnect between motivation and capabilities is far too wide, making an attack in the foreseeable future highly unlikely. But in the mid- to long-term three factors in particular; namely increasing Muslim alienation with U.S. policies, growing proliferation of knowledge and technology and the increasingly rootless and ubiquitous nature of global jihad, are likely to converge, thus rendering a WMD attack all but inevitable.
1. See e.g. Salah, Muhammad. 1999. Bin Laden Front Reportedly Bought CBW From East Europe. Al-Hayat 20/4/1999.
2. Al-Matrafi, Saad. 2005. Terrorist Website Drops Dirty Bomb. Arab News 11/03/2005. https://www.arabnews.com/?page=1§ion=0&article=60255&d=11&m=3&y=2005.
3. For more information on Saudi financing see Bahgat, Gawdat. 2004. Saudi-Arabia and the War on Terrorism. Arab Studies Quarterly 26:1., pp. 51 – 64.
4. See al-Fahd, Naser. 2003. Risalah fi hukm istikhdam aslihat al-damar al-shamel didh al-kuffar, Rabi` Awwal 1424H https://www.al-fhd.com/rsayl/doc/rsayl.damar.doc.
5. Hisham al-Qarwi, “Bin Ladin’s Local Deputies,” Al-Arab al-Alamiyah 8/11/2002.
6. Abu Nasr, Muhammad. 2005. Chemical Warheads Suspected In Attack on US Base. Free Arab Voice 24/02/2005.
7. Al-Faris, Omar and Abu Nasr, Muhammad. 2005. Use Of Sarin Gas Suspected In Fallujah Withdrawal. Free Arab Voice and Islam Memo 18/02/2005.
8. La Voix des Opprimés 29.4.2005 https://www.stcom.net/.