India’s financial capital, Mumbai, experienced yet another terrorist attack today that initial estimates say killed at least 20.

Terrorists detonated improvised explosive devices (IEDs) in three separate locations of the city almost simultaneously. The first two blasts occurred at around 6:55 pm, one in a jewelry market and one in a business district in southern Mumbai. The third blast occurred around 7:05 pm in a crowded neighborhood in central Mumbai.

This is the most significant terrorist attack in India since the three-day Mumbai shooting attacks in November 2008 that killed nearly 170. There was an attack on a German bakery in Pune, India, in February 2010 that killed nine. But since then, India had gone almost 18 months without experiencing a major terrorist attack.

It is too early to determine who is responsible for the attacks, but Indian authorities are pointing to the possibility of the Indian Mujahideen (IM), a homegrown outfit with links to the Pakistan-based Lashkar-e-Tayyiba (LeT).

The strength of the links of these bombings to the LeT will determine how India responds. If investigators determine that LeT members played a crucial role in the planning and implementation of today’s attacks, the Indian leadership will be compelled to again break off recently resumed talks with Islamabad.

If, on the other hand, investigations show that the IM carried out these bombings largely on its own, there will be less pressure on Indian leaders to immediately withdraw from the Indo–Pakistani dialogue.

In the six months before the November 2008 attacks (which were clearly carried out by the LeT), India suffered several terrorist attacks inside the country, most of which were claimed by the IM. This led to concern in India about the growing threat posed by homegrown Islamist extremists. Interestingly, Indian authorities yesterday arrested two IM members for their involvement in attacks in Ahmedabad, India, in the summer of 2008 that killed nearly 60.

There will be speculation in India that elements within Pakistan opposed to peace talks directed the attacks in order to halt dialogue. The attacks also occur at a time of high turmoil within the Pakistan military over the bin Laden operation and deteriorating relations with the U.S.

Given the current uncertainty within the Pakistan military and volatile situation inside Pakistan, Indian leaders may be loath to escalate tensions with Pakistan.

U.S. officials should do everything they can to counsel calm in both Islamabad and New Delhi. They should also make clear to Pakistani officials that, whether or not the attack originated in Pakistan, now would be an opportune time to move ahead with the prosecutions of the LeT members involved in the 2008 attacks to show their good faith and help keep dialogue with India on track.