Defence Minister Manohar Parrikar Monday called on Asian countries for action against terrorism, describing it as the "most pervasive and serious threat"."Terrorism remains the most pervasive and serious challenge to global security while threat of terror is transnational. The response doesn't seem so," Parrikar said."A collective action should come from Asia," he added.He was speaking at the 19th Asian Security Conference being held here at the Institute of Defence and Studies and Analyses.The theme of the conference this year is "Combating Terrorism: Evolving an Asian Response".