NEW DELHI:US deputy secretary of state Stephen Biegun on Tuesday suggested formalisation of Quadrilateral or Quad to deal with the prevailing global challenges, but underlined it was premature to talk about its expansion at this stage. He also emphasised that Indo-US ties are much bigger than one political party. The remarks followed Biegun’s trip to India last week. The comments are significant considering that Australia has returned to the Malabar exercise after over a decade and after the Quad ministerial meet in Tokyo earlier this month. “It is our view that in the passage of time, the Quad should become more regularised and, at some point, formalised as well, as we really begin to understand what the parameters of this cooperation are and how we can regularise it,” Biegun noted. He said the Quad remains a “somewhat undefined entity” and it was premature to talk about expanding it.