New Delhi, Apr 1 - India should have sent its troops back to Sri Lanka to kill or capture Prabhakaran and the LTTE leadership after the assassination of Rajiv Gandhi, says a new book by a former US diplomat. Rajiv Gandhi's killing was an attack on India's status as a regional power. Forcibly bringing Prabhakaran to India to face trial would have sent a clear message to the region, and the world, that India would defend its political leaders from attack, defend its political system from intimidation and defend its primacy in South Asia against any challengers, the author says.