The bloody terrorist attacks in Mumbai, India, have the potential to cascade across the region. If Pakistan’s army and intelligence service, which have long supported anti-India terrorist groups, are deemed responsible for the attacks, the results could be catastrophic.

In 2001, an attack on the Indian parliament, carried out by Pakistan-based Islamist terrorists, brought the two countries to the brink of nuclear war.

This time, even if it doesn’t go that far, the results could be far deadlier than the attacks themselves, which killed more than a hundred people. The assault could upend the peace process now underway between Pakistan and India. That, in turn, would strengthen the hand of Pakistan’s military establishment, which is already brooding about the new civilian government that replaced President Musharraf, the army dictator. And the army could use the renewed tension to redouble its alliance with radical-right, anti-Indian Muslim groups in Pakistan and Afghanistan. By doing so, the idea of negotiations between various Islamists components of the Taliban movement, on one hand, and the civilian governments of President Karzai in Afghanistan and President Zardari in Pakistan, on the other, might be put on indefinite hold.

It isn’t completely clear yet who was responsible for the Mumbai attacks, but it seems almost certain that the terrorists had professional help, and that they have ties — or once did — to the ISI, Pakistan’s intelligence service. The ISI chief, newly installed, is going to visit India to assist in the investigation, which suggests that the attackers, if they once had ISI ties, no longer do. But India’s prime minister has blamed elements “based outside the country,” and India’s foreign minister said “some elements in Pakistan are responsible.”

Bruce Riedel, a former National Security Council expert on South Asia, who led Barack Obama’s advisory task force on Pakistan, has written how the 2001 attack on the Indian parliament may have been carried out by ISI-connected Kashmiri terrorists. The attack, he said, protected Osama bin Laden, then under assault by US forces invading Afghanistan Bin laden was scuttling over the Afghan-Pakistan border, and Pakistan’s forces weren’t there to seal the border, despite Musharraf’s pledge to the Bush administration to help nab Al Qaeda leaders. “By diverting Pakistan’s army to the east, to the border with India for the next year, the Parliament attack helped save Al Qaeda,” wrote Riedel.

The attacks could vastly complicated the problem that Obama will face in Afghanistan, where US and NATO forces are losing the war, and in Pakistan, where Islamist militants have seized control of large areas in that country’s northwest region. Obama is already committed to an escalation of the Afghan war, and if the prospects for negotiations recede, he may be tempted to send even more US forces into that quagmire.