India is marking two years since gunmen launched co-ordinated attacks in the western city of Mumbai (Bombay), killing 166 people.
Commandoes marched through the streets of south Mumbai and Home Minister Palaniappan Chidambaram laid a wreath at a police memorial in the city.
Prime Minister Manmohan Singh pledged "to redouble efforts to bring the perpetrators of the crime to justice".
Mourners are expected to commemorate the day with prayers and peace marches.
The 60-hour siege targeted luxury hotels, the main railway station and a Jewish cultural centre.
Meanwhile, India has rebuked Pakistan for not pressing ahead with charges against the alleged masterminds.
Security is tight across Mumbai with anti-terrorist police among those deployed, Joint Police Commissioner Rajnish Seth said.
"The main purpose is to pay homage to the martyrs and to reassure the people that they are safe and secure," Mr Seth told Bloomberg news agency.
'Designs of enemies'
Newly formed crack commando teams and police forces participated in the march which began at the Oberoi Trident Hotel, one of the sites of the attacks.
State of the art weaponry and vehicles, which the Mumbai police have acquired since the attacks, were displayed at the parade.
Watched by family members of many of those killed in the attacks, Mr Chidambaram laid a wreath at the martyrs' memorial and observed a minute's silence.
In Delhi, Prime Minister Manmohan Singh issued a statement pledging to punish the attackers.
"On this day of remembrance, we salute the courage, unity and the resolve of ordinary Mumbaikars [residents of Mumbai] and the brave and selfless action of our men in uniform during the attack," PM Singh said in a statement.
"It is this spirit and strength of character of the Indian people that will defeat such forces that seek to threaten our social fabric and way of life.
"We will never succumb to the designs of our enemies," he said.
On the city's Chowpatty Beach, police officers are due to unveil a memorial to Tukaram Ombale, a constable killed during the attack.
Although tourism declined in the wake of the attacks, tour operators say visitors are returning to Mumbai in record numbers.
On his trip to India earlier in November, US President Barack Obama visited the city and stayed in one of the luxury hotels targeted by the gunmen, Taj Palace Hotel - now fully restored.
On Thursday, US Secretary of State Hilary Clinton said the American people stood in solidarity with the people of India and would honour those who lost their lives.
Nine of the gunmen were killed during battles with security forces as the siege wore on.
The sole survivor, Pakistani citizen Mohammed Ajmal Qasab, was condemned to death by a Mumbai court in May.
Seven others, who are allegedly linked to the militant group Lashkar-e-Taiba, have been charged in Pakistan but have not gone on trial.
In a statement, India's ministry of external affairs said that despite reassurances by Pakistan "substantive and verifiable progress has not been made on bringing all the perpetrators and masterminds of the heinous attacks to justice".
Pakistan has said the legal case is continuing.