On June 10, 2014, militants of the Islamic State in Iraq and Syria (ISIS) marched into Mosul, Iraq's second-largest city. In quick succession, they captured a large swathe of northern Iraq and consolidated their control over parts of Syria.
Today, two years after the fall of Mosul, ISIS has in many ways overshadowed Al-Qaeda as the world's deadliest terrorist organisation.
Western and Middle Eastern security officials now view ISIS as the greater threat to their domestic security, especially because of its mastery of social media and its ability to recruit thousands of disenchanted young Muslims into its ranks. Federal Bureau of Investigation director James Comey warned at a security forum last summer that ISIS "is not your parents' Al-Qaeda".
But even in its weakened state, Al-Qaeda still poses a danger to the West, the Middle East and the wider Muslim world. In recent years, Al-Qaeda has become more active in Yemen and it has established a strong affiliate in Syria, the Nusra Front, which is a dominant force among the extremists fighting the regime of Syrian President Bashar al-Assad.
Since 2013, ISIS and Al-Qaeda have been competing for funding, recruits and prestige - and they often argue over tactics.
ISIS leaders prefer the wholesale slaughter of civilians, as epitomised by recent attacks in Paris, Baghdad, Beirut and elsewhere. By late 2014, ISIS had seized large chunks of territory in Syria and Iraq. ISIS then proclaimed a caliphate in the territory under its control, and named its leader, Abu Bakr al-Baghdadi, as caliph and "leader of Muslims everywhere".
ISIS established a territorial base that has allowed it to govern territory, train thousands of fighters and generate income from illicit trade in oil and other resources - all on a scale larger than anything Al-Qaeda had achieved. ISIS has also established a larger recruitment effort and more sophisticated social media presence than Al-Qaeda.
With its self-declared caliphate, ISIS has gained control of more resources and generated far more income than Al-Qaeda. ISIS generates money by selling oil and wheat, imposing taxes on residents of the territory it controls, and through extortion.
In 2014, ISIS raked in about US$2 billion (S$2.7 billion), according to the US Treasury Department. That included US$500 million in oil sales on the black market, and up to US$1 billion in cash stolen from banks as the group made its initial march across Syria and Iraq. By contrast, Al-Qaeda has historically relied on donations from wealthy individuals, especially in the Gulf Arab states.
Overall, ISIS has displaced Al-Qaeda as the dominant force in international jihadism. But it is important not to underestimate Al-Qaeda's ability to evolve and adapt to a new landscape - as it has done before.
When the United States invaded Afghanistan in October 2001 to drive out the ruling Taleban movement that sheltered Osama bin Laden and his supporters, Al-Qaeda was thrown off balance. But it quickly regrouped, dispersing its surviving members, distributing its ideological tracts and terrorist techniques to a wider audience on the Internet and encouraging new recruits to act autonomously under its banner.
ISIS and Al-Qaeda differ in other important ways: Al-Qaeda wants to overthrow what it views as the corrupt and "apostate" regimes of the Middle East - the "near enemy". But in order to do so, Al-Qaeda's leaders focused on the "far enemy:" the US and the West.
These are also the places that spawned the top leaders of Al-Qaeda: Osama was a Saudi, while his top lieutenant, Ayman al-Zawahiri, is Egyptian. We will never know whether these men would have attacked the US regardless of its support of the governments they were trying to destroy. Both men at first turned against the dictators at home, and then - realising that the US was helping to prop up these regimes - they targeted the "far enemy".
In targeting the US, Al-Qaeda believes it will force Washington to withdraw its support for the autocratic Arab regimes and abandon the Middle East entirely.
But ISIS does not subscribe to Al-Qaeda's vision and instead focuses on the "near enemy" - meaning the so-called apostate regimes in Syria, Iraq and other parts of the Arab world. So far, ISIS has been more successful in its strategy, which relies on capturing and holding territory.
As Al-Qaeda's influence waned, ISIS has tried to fill the vacuum by expanding into new territory. In November 2014, Baghdadi announced that he was creating new "provinces" of his self-declared caliphate in five new countries: Saudi Arabia, Yemen, Libya, Algeria and Egypt. While ISIS sympathisers had pledged allegiance to Baghdadi in other states, including Lebanon, Afghanistan and Pakistan, the ISIS leader singled out only those countries where the movement has a strong base of support and could mount sustained attacks.
But Baghdadi also called on his supporters to carry out "lone wolf" attacks wherever possible. "Oh soldiers of the Islamic State, erupt volcanoes of jihad everywhere," he declared. "Light the earth with fire against all dictators."
And for more than a year, ISIS militants have been heeding the self-proclaimed caliph's call.
ISIS is the stronger organisation now but Al-Qaeda's ability to regroup should also give pause to the anti-terror fight. Neither group should be underestimated.
The writer is a journalism professor at New York University and a former Middle East bureau chief at New York paper Newsday.
A version of this article appeared in the print edition of The Straits Times on June 10, 2016, with the headline 'ISIS pulls ahead of Al-Qaeda'. Print Edition | Subscribe
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