Defence Minister Manohar Parrikar on Monday called on Asian countries to take action against terrorism, describing it as the "most pervasive and serious threat"."Terrorism remains the most pervasive and serious challenge to global security while the threat is transnational... even when there is broad consensus on what constitutes act of terror, a formal agreement is missing," he said in his address at the 19th Asian Security Conference being held at the Institute of Defence and Studies and Analyses here. The theme of the conference this year is "Combating Terrorism: Evolving an Asian Response".Terming as "central" Asia's role in the fight against terror, Parrikar said: "Seven out of top ten countries having the highest adverse impact (from terrorism) are coming from Asia.. The initiative of global response has to come from Asia." "A global response to terrorism can only emerge if there is a regional consensus on issues effecting the countries involved," he said."A strong regional push from Asia will exert more pressure on the rest of the world to adopt a cohesive framework to fight all terror group, he added.On the Indian role in the fight against terror, the Minister said: "India can't afford to distance itself from happenings in the Asian countries."