Bush spoke at the White House after returning from the Camp David presidential retreat where he spent Thanksgiving and monitored the rampage. The coordinated assaults left nearly 200 people dead, including six Americans, and raised tensions between India and neighboring Pakistan, two nuclear-armed rivals.
"The killers who struck this week are brutal and violent," Bush said on the South Lawn with first lady Laura Bush at his side. "But terror will not have the final word. The people of India are resilient. The people of India are strong. They have built a vibrant, multiethnic democracy. They can withstand this trial."
Before leaving Camp David in the mountains of Maryland, he held an hour-long video-teleconference with U.S. diplomats in India. He said his administration had kept President-elect Barack Obama informed since the siege began Wednesday.
"We pledge the full support of the United States as India investigates these attacks, brings the guilty to justice and sustains its democratic way of life," Bush said.
"The leaders of India can know that nations around the world support them in the face of this assault on human dignity. And as the people of the world's largest democracy recover from these attacks, they can count on the people of the world's oldest democracy to stand by their side."
Those participating in the videoconference included Secretary of State Condoleezza Rice; David Mulford, the U.S. ambassador to India; Paul Folmsbee, consul general at the U.S. consulate in Mumbai; and members of Bush's national security team. "President Bush thanked our ambassador and our consul general for all the work they've done to help Americans affected by the terrorists," White House press secretary Dana Perino said.
Obama called Indian Prime Minister Manmohan Singh on Friday night to offer condolences and was monitoring the situation. The attacks, which killed at least 195 people, including 18 foreigners, in India's financial capital, ended Saturday when commandos killed the last three gunmen inside a luxury hotel.
FBI agents were en route to India on Saturday. A second group of investigators was on alert to join the first team if necessary. The State Department warned U.S. citizens still in the city that their lives remain at risk.
"The FBI continues to monitor the situation in Mumbai and the Counterterrorism Division is reviewing all of the information and intelligence available," bureau spokesman Richard Kolko said.
A previously unknown Muslim group with a name suggesting origins inside India claimed responsibility, but Indian officials said the sole surviving gunman was from Pakistan and they pointed a finger of blame at Pakistan, which vehemently defended itself against allegations that it was involved in the attacks.
Pakistan's ambassador to the U.S., Husain Haqqani, said in a statement that his country is "confronting the menace of terrorism with great vigor." Haqqani insisted "it is unfair to blame Pakistan or Pakistanis for these acts of terrorism even before an investigation is undertaken."
The U.S. is concerned about a potential flare-up between India and Pakistan. To ease tensions, intelligence officials are searching for clues that might identify the attackers even as Indian officials claim "elements in Pakistan" were involved.
A U.S. counterterrorism official said some "signatures of the attack" were consistent with the work of Pakistani militant groups known as Lashkar-e-Taiba and Jaish-e-Mohammed that have fought Indian troops in the disputed Himalayan region of Kashmir and are reported to be linked to al-Qaida. But the official emphasized it was premature to pinpoint who was responsible for the attacks. The official spoke on condition of anonymity due to the sensitivity of the situation.