Though these latest threats do not adhere to al Qaeda's usual playbook, they are consistent with the strategy of several linked Kashmiri militant groups operating in India. These groups increasingly are being drawn into the jihadist orbit -- a development with grave implications for both New Delhi and Islamabad.

Security was beefed up at airports throughout India on Nov. 13 after two threatening messages from al Qaeda were discovered in the past week. A janitor at Tiruchirapalli Airport discovered the first threat, a handwritten letter in Tamil saying al Qaeda would attack Chennai International Airport with "sophisticated technology" as it did in Thailand. The letter also said about 10 suicide bombers would carry out attacks in airports in Tiruchirapelli, Madurai and Coimbatore in the southern Indian states of Tamil Nadu and Kerala. The FBI then warned the Indian government Nov. 12 that it had intercepted an e-mail referring to possible al Qaeda attacks at airports in major Indian cities and hijackings on U.S.- and Europe-bound planes departing India.

Though these latest threats diverge from al Qaeda's usual pattern, they do bear the hallmarks of several allied Kashmiri militant groups operating in India. Increasingly, these groups are becoming aligned with the jihadists -- something with serious implications for India and Pakistan.

Many Kashmiri militant groups operating in India find it beneficial to adopt the al Qaeda brand to enhance their credibility. The reference in the letter to a failed attack in Thailand stands out, however. Though the precise connection between the new letter and the Thai operation is not clear, a little-known al Qaeda plot in Thailand was thwarted in March 1994. That plot involved Ramzi Yousef, the convicted mastermind of the 1993 World Trade Center bombing. The plotters planned to use a vehicle-borne improvised explosive device consisting of ammonium nitrate and diesel fuel to destroy the Israeli or U.S. Embassy in Bangkok.

The airport threat authors' awareness of the Thai plot lends credence to their claimed linkage to al Qaeda's core leadership -- though information relating to plots routinely percolates through Islamist militant channels. Though knowledge of past attacks itself generally does not mean much, since the failed Thailand plot remained very low key, mentioning it allows the militants to frighten security and intelligence officials (especially U.S. and Western ones) who have watched al Qaeda over a long period of time.

Historically, al Qaeda's core leadership has paid only limited attention to India, though Osama bin Laden mentioned India in a recent communique. Since al Qaeda lacks its own structure in India, it relies on groups such as Lashkar-e-Taiba (LeT) to act on its behalf. Al Qaeda thus limits itself to providing support and guidance, leaving tactical issues to local operatives. But India has no strong Islamist militant current to tap for support. Moreover, al Qaeda fears being cornered by both Pakistani and Indian forces -- something militant attacks could provoke. This, along with the fact that the letter is in Tamil, backs the view that an indigenous militant group staged the airport threat, not al Qaeda prime or even a Kashmiri militant group.

Islamist militant groups based in Pakistani-controlled Kashmir, on the other hand, increasingly have cooperation with al Qaeda affiliates that belong to the broader transnational jihadist movement. The have focused on operations in India beyond northern India and the Indian state of Jammu and Kashmir. LeT and its splinter groups also appear increasingly influenced by al Qaeda in exploring new, more spectacular tactics to magnify their status in the Kashmiri insurgency, including sending militants to flight school in Bangalore and inciting Hindu-Muslim sectarian attacks by targeting Muslim worshippers.

Though al Qaeda typically does not give warnings ahead of major attacks, Kashmiri militant groups have a pattern of issuing a series of bomb hoaxes and threatening letters before attacks . Before the July 11 Mumbai railway bombings, the number of threats against railway stations throughout India confounded the security forces. By delivering these threats militants can try to wear out Indian security and intelligence forces and evaluate the security response at the target.

Parallel to India, Pakistani authorities also placed all 36 of Pakistan's airports on high alert. Those in the southwestern province of Balochistan, such as in the cities of Quetta and Gwadar, were placed on "red alert." The move illustrates how Islamabad faces its own surge of jihadist violence after the Oct. 30 airstrike on a madrassa in the country's northwestern tribal belt.

Whether the Pakistani move is related to the Indian move remains unclear, but in 1999 Kashmiri Islamist militants linked to al Qaeda hijacked a Kathmandu-New Delhi Indian commercial flight, diverting it to Kandahar during the time of Taliban rule. The Quetta area in particular is known as a hub for Taliban activity; it borders the Afghan province of Zabul, a hotbed of that nation's Pashtun jihadist insurgency. Considering the links among the Taliban, al Qaeda and Kashmiri jihadists (all of which operate from Pakistan), a plot for a coordinated attack or hijacking is quite plausible.

With India and Pakistan preparing to restart another round of heretofore futile peace talks, a major attack could well be in store to influence the negotiations. Through its intelligence apparatus, Islamabad holds a considerable degree of influence over the mainstream Kashmiri militant organizations. Many groups, however, including LeT, al Badr and Jaish-e-Mohammed and their affiliates in the Students Islamic Movement of India have become much more autonomous in their operations. This could further complicate matters for Pakistani President Gen. Pervez Musharraf, who is already struggling to juggle Washington and his domestic constituency.

Ultimately, Indian airports and domestic flights are especially vulnerable to bombings and hijackings. With the Islamist militant movement giving rise to more cells in southern India, the information technology sector in Bangalore and Hyderabad would make prime targets. Kashmiri militant outfits strongly desire to stage a more spectacular attack to elicit the response they failed to get from the Mumbai railway bombings; it may only be a matter of time before they get their wish.