With tensions heightened between India and Pakistan, the top American envoy is calling for Islamabad to show its resolve and to join the international effort to find those responsible for the Mumbai terror attack.  U.S. Secretary of State Condoleezza Rice made the remarks in the Indian capital where she met with Prime Minister Manmohan Singh and other top Indian government officials.  VOA Correspondent Steve Herman reports from New Delhi.

US Secretary of State Condoleezza Rice (l) and India's External Affairs Minister Pranab Mukherjee in New Delhi, 03 Dec 2008

India's government says all options are on the table in dealing with neighbor Pakistan in wake of the unprecedented terror attack on Mumbai.

India External Affairs Minister Pranab Mukherjee, with U.S. Secretary of State Condoleezza Rice at his side, told reporters there is no doubt the terrorists who struck the country's commercial capital came from Pakistan and were coordinated there.

"Government of India is determined to act decisively to protect its territorial integrity and the right of our citizens to a peaceful life with all the means at our disposal," Mr. Mukherjee said.

Secretary Rice gave a diplomatic answer when questioned by a reporter if the United States would support a military strike by India on suspected terrorist infrastructure inside Pakistan.

"Any response needs to be judged by its effectiveness in prevention and also by not creating other unintended consequences or difficulties," she said.

India and Pakistan, which both have nuclear weapons, have gone to war against each other three times.

Indian soldiers aim a grenade launcher at part of the facade of the Taj Mahal hotel in Mumbai, 28 Nov 2008

India blames the Mumbai attack on 10 gunmen who came by sea from Pakistan, heavily armed with automatic weapons and hand grenades.  They killed about 175 people during a 60-hour siege.

New Delhi has formally requested Islamabad hand over 20 Indians and Pakistanis believed to be in Pakistan.

Secretary Rice says the United States expects Pakistan to fully cooperate with India in determining who is responsible for the Mumbai attack and helping to bring them to justice.

Although some U.S. officials suspect involvement of the Pakistan-based Lashkar-e-Tayyiba terorist group, Secretary Rice says it is premature to draw conclusions about who is responsible.  She notes the assault on India's commercial capital was sophisticated in the style of an al-Qaida terrorist act.

Rice is to fly Thursday to Islamabad as part of her altered itinerary that had her detour from Europe to South Asia, following last week's attack by terrorists on Mumbai.

A number of other prominent Americans have come to the region to hold talks with Indian and Pakistani officials.  They include three senior American senators and the chairman of the Joint Chiefs of Staff, Admiral Mike Mullen.

In Islamabad, the admiral asked Pakistani leaders to aggressively look into possible links between groups in the country and the Mumbai attack.

Pakistan denies any link between the attack and government agencies, but says "non-state actors" might have been involved.