New Delhi, Oct. 21 -- The Quadrilateral Security Dialogue or Quad should become more regularised and formalised so that there are modalities for cooperation and interoperability among its members for dealing with global challenges, US deputy secretary of state Stephen Biegun said on Tuesday.

Biegun, who was on week-long visit to India and Bangladesh last week, was speaking ahead of the India-US 2+2 ministerial dialogue expected to be held during October 26-27 and the Malabar military exercise in November that will be joined by the navies of all the Quad members - Australia, India, Japan and the US. The top US diplomat also criticised China for not doing enough to help find a long-term solution the issue of more than 800,000 Rohingya refuge...