Al Qaeda has a new franchise: Qaedat al-Jihad in the Indian Subcontinent. On Wednesday, Ayman al-Zawahiri, widely believed to be in hiding in Pakistan, appeared in a video announcing the creation of the jihadist group's latest offshoot. It will be led by Asim Umar, a somewhat obscure militant best known for an online video calling on Indian Muslims to sign up for a global jihad. Zawahiri says the group will "raise the flag of jihad, return Islamic rule, and empower the Sharia of Allah across the Indian subcontinent."
Mr. Zawahiri's threats should be taken seriously. However, the bigger danger to India is al Qaeda's rival for leadership of global jihadism: the terrorist group ISIS, also known simply as Islamic State. Al Qaeda may well have deeper networks in the subcontinent. But in terms of both sophisticated messaging and raw appeal, the 63-year-old Egyptian doctor's outfit cannot match the ISIS upstarts who burst into the public eye after capturing Mosul, Iraq's second largest city, in June.
Consider the evidence. At least four Indian Muslims have reportedly signed up to fight with ISIS in Iraq. Last week, one of them, a 22-year-old engineering student named Arif Majeed, was reported killed, possibly in a U.S. airstrike. He left behind a letter to his family in which he explained his reasons for traveling from his home outside Mumbai to Iraq: "It is a blessed journey for me, because I don't want to live in this sinful country."
Meanwhile, police in the southern state of Tamil Nadu arrested a Muslim cleric after a group photo of young Muslim men posing outside a mosque in ISIS T-shirts began to circulate on social media.
These may be isolated incidents, and the vast majority of Indian Muslims shows no signs of being attracted to any jihadist group. But ISIS has arguably made a bigger splash in India in three months than al Qaeda could manage in the 26 years since it was founded in Pakistan by Osama bin Laden.
ISIS enjoys many advantages that so-called core al Qaeda, the parts of the network based in Pakistan and Afghanistan, lacks. First, in terms of the kind of symbolism that fires up jihadists, it's hard to beat the re-establishment, at least notionally, of a caliphate uniting all believing Sunni Muslims. ISIS controls an estimated 35,000 square miles of territory, about the size of Jordan. The group has effectively erased the border between Iraq and Syria created by an agreement between Britain and France in 1916.
Moreover, the U.S. invasion of Afghanistan in 2001, a longstanding drone campaign, and the successful killing of bin Laden in 2011 have forced prominent al Qaeda leaders such as Mr. Zawahiri to lie low. ISIS leader Abu Bakr al-Baghdadi, known to his followers as Caliph Ibrahim, is rarely in the public eye. But he enjoys enough freedom of movement to have recorded a propaganda video of a sermon he delivered at a mosque in Mosul.
Mr. Baghdadi's sermon calling the faithful to his self-proclaimed caliphate was only one part of a sophisticated media strategy. By posting videos and pictures of beheadings, mass executions and public crucifixions, ISIS has learned how to use social media to both scare opponents and attract bloodthirsty new recruits from around the world. By one estimate, its ranks include 700 French citizens, 400 Britons and 250 Australians, as well as thousands of Arabs.
Simply put, today ISIS represents what al Qaeda once did—the world's largest single grouping of jihadists bound by a common faith in a hard-line interpretation of Islam. ISIS has already subtitled a recruitment video titled "The Chosen Few of Different Lands" in at least three Indian languages: Urdu, Hindi and Tamil. This suggests that it views India as a promising target for growth.
How well prepared is India for the threat of radicalization that ISIS represents? Many of the country's politicians and intellectuals remain caught in a time warp when it comes to the Middle East. For them, paying attention to the region rarely goes beyond mouthing tired slogans of solidarity with the Palestinians beloved of the global Left.
An Indian journalist is more likely to travel to Gaza to pen a story on alleged Israeli oppression, then to visit, say, Mosul or the de facto ISIS capital of Raqqa in northern Syria. With an eye on their Muslim constituents, many Indian politicians practically fall over each other to condemn Israel, but there is no clamor among them to discuss developments that potentially threaten the safety of India itself.
Add to this India's failure to modernize its 150-million strong Muslim minority. Unlike in the West, where one law for all citizens is a cornerstone of secularism, India allows its Muslims to follow Sharia in matters of marriage, divorce and inheritance. In the end, ISIS, like al Qaeda, is fighting to impose its harsh interpretation of Sharia on the world. By bowing to Sharia at home, India has helpfully decided to meet them halfway.
None of this is to suggest that al Qaeda has ceased to be dangerous. If anything, its long presence in the subcontinent gives it deeper links with indigenous jihadists, such as Pakistan's Lashkar-e-Taiba. But if the biggest danger India faces from jihadist groups is the radicalization of part of its Muslim population, then it's ISIS, not al Qaeda, that ought to worry New Delhi more.
Mr. Dhume is a resident fellow at the American Enterprise Institute and a columnist for WSJ.com. He tweets @dhume.