did they carry out any suicide attacks?
Yes, their mission included carrying out suicide attacks against enemy targets.
Liberation Tigers of Tamil Eelam
One of the main divisions of LTTE included the Black Tigers, an elite fighting wing of the movement, whose mission included carrying out suicide attacks against enemy targets. 
how many tamils are there in sri lanka 70% since how long have they been living here? Sri Lankan Tamils have a very long history in Sri Lanka and have lived on the island since at least around the 2nd century BCE. are they genetically linked to other sri lankans? Yes,  genetic studies indicate that they are closely related to the Sinhalese ethnic group in the island. which religion do they follow? The Sri Lankan Tamils are mostly Hindus with a significant Christian population. was there any militancy related to them? Yes, Liberation Tigers of Tamil Eelam (LTTE) what was its goal? Its aim was to secure an independent state of Tamil Eelam were they declared as a terrorist organization? Yes, 32 countries currently list the LTTE as a terrorist organisation.
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Liberation Tigers of Tamil Eelam [SEP] Suicide attacks
One of the main divisions of LTTE included the Black Tigers, an elite fighting wing of the movement, whose mission included carrying out suicide attacks against enemy targets. From ancient times, the Tamil civilisation saw war as an honourable sacrifice, and fallen heroes were revered and worshiped in the form of a Hero stone. Heroic martyrdom was glorified in ancient Tamil literature. The Tamil kings and warriors followed an honour code similar to that of Japanese Samurais and committed suicide to save the honour. The Black Tigers wing of the LTTE is said to reflect some of these elements of Tamil martial traditions including the practice of the worship of fallen heroes (Maaveerar Naal) and martial martyrdom.