Facing the 'undeniable' threat of another Mumbai-type attack by Pakistan-based terror groups, which may act under Al Qaeda's direction, India is most likely to retaliate militarily in such a scenario, according to a prominent American think tank.
"The threat of another Mumbai-type attack is undeniable; numerous Pakistan-based groups remain motivated and able to strike Indian targets," said Daniel Markey of the prestigious Council on Foreign Relations in his latest paper 'Terrorism and Indo-Pakistani Escalation.'
Many of these Pakistan-based terror groups have incentives to act as spoilers, whether to disrupt efforts to improve Indo-Pak ties or to distract Islamabad from counter-terror crackdown at home, said Markey, a known South Asia expert.
"Thus the immediate risk of terrorism may actually increase if New Delhi and Islamabad make progress on resolving their differences or if Pakistan-based terrorists are effectively backed into a corner," he said in his 11-page contingency planning memorandum of the CFR.
While traditionally Pakistan-based Lashkar-e-Tayiba and Jaish-e-Mohammed are the two terror groups that have proven themselves the most capable and motivated to carry out attacks in India, this time Al Qaeda could don the mantle, he said.
"Al Qaeda has historically focused its efforts outside India, but if the group's leadership feels threatened in the Pakistan/Afghanistan border areas, it might direct and assist regional proxies to attack India as a way to ignite a distracting Indo-Pakistani confrontation," the report stated.
Other regional terrorist groups, including those based in India, are improving their capacity to inflict mass-casualty violence, but because these outfits lack clear-cut connections to Pakistan-based organisations, their attacks are far less likely to spark another crisis between India and Pakistan, Markey said.
He said the more clearly a terrorist attack can be identified as having originated in Pakistan, the more likely India is to retaliate militarily.
He said groups that India perceives to have closer links with Pakistan's military and intelligence establishment -- especially LeT -- are more likely to 'inspire retaliation against official Pakistani state targets' than those that are perceived as more autonomous, such as the Al Qaeda.
The perception in India that Islamabad has responded inadequately to the Mumbai attacks -- trials of accused plotters are moving slowly and LeT ideologue Hafiz Muhammad Saeed is not in custody -- strengthens Indian advocates for unilateral military retaliation, Markey said.
Should multiple attacks occur in quick succession, the cumulative effect would further diminish India's inclination for restraint, he said.
"Prime Minister Manmohan Singh has been a strong voice against Indian military retaliation, but his voice could be silenced by a future attack or otherwise drowned out by domestic political pressures," Markey said.
Markey said if New Delhi determines that its assailants acted with little or indirect assistance from Pakistan's military or intelligence agencies, its most likely response would be to conduct air strikes against suspected terrorist training camps in Pakistan.
"During these operations, India would attempt to limit civilian casualties and direct combat with the Pakistani military to reduce the prospects for escalation. Such an attack would not significantly curtail the terrorist threat, but it might satisfy India's domestic compulsions to punish the perpetrators," he said.
Markey said the more egregious the terrorist attack and the more India's leadership is convinced that members of the Pakistani state sponsored it, the more it will be treated as an act of war.
"Under these conditions, New Delhi would consider a wider range of options, including, for instance, a large ground-force mobilisation of the sort India conducted in 2001-2002 in the wake of the terrorist attack on the Indian parliament or a naval blockade."
"Unless the initial terrorist attack is nuclear -- which is implausible for now because Pakistani terrorists do not appear to have access to nuclear materials or the capacity to utilise them -- India would refrain from using its nuclear weapons in retaliation," Markey said.
He said Pakistan's leaders would come under tremendous domestic pressure -- and for the most part would be inclined -- to counter nearly any sort of Indian military retaliation.
Even the least invasive of India's possible military options, 'such as a resumption of artillery shelling across the Line of Control,' Pakistan's military and civilian leadership would be consumed by the crisis and distracted from other issues, Markey said.
"Pakistan's military response could be intentionally disproportionate to the initial Indian attack so as to compel the international community to force a ceasefire," he added.
"That said, Pakistan's present government and military command also have meaningful incentives to calibrate their actions from the start, not least the desire to limit international pressure and to retain ties with partners in Beijing, Riyadh and Washington," he said.
However, Markey said a military exchange between India and Pakistan sparked by a terrorist attack in India is not likely to cross the nuclear threshold.
Several conceivable circumstances could alter this conclusion, but two stand out: "(1) India suffers additional catastrophic terrorist attacks in the midst of the crisis, driving it to intensify the conflict to a point where Pakistan's army determines it cannot defend the state by conventional means, and (2) Pakistan's nuclear command, as yet untested by major conventional attacks, is blinded or confused to the point that it authorises a first strike," the report stated.