Twenty-one years ago on December 13, terrorists of the Lashkar-e-Taiba (LeT) and the Jaish-e-Mohammed (JeM) attacked the Parliament complex and opened fire, killing nine people.
"I pay tribute to the warriors of the country who laid down their lives to protect the honour of India on this day in 2001, during the cowardly terrorist attack on Parliament," Gandhi said in a tweet in Hindi.
"The whole country is indebted to their sacrifice that inspires us to devote everything in the service of the country," he said.
The attack victims included five Delhi police personnel, a woman Central Reserve Police Force (CRPF) trooper, two Parliament watch and ward staff and a gardener. A journalist who was injured died later. All five terrorists were shot dead.