The U.S. State Department’s No. 2 diplomat said Monday that Washington was aiming to “formalize” growing strategic ties with India, Japan and Australia in a forum known as “the Quad" — a move experts say is implicitly designed to counter China in the Indo-Pacific region.

"It is a reality that the Indo-Pacific region is actually lacking in strong multilateral structures. They don't have anything of the fortitude of NATO, or the European Union," U.S. Deputy Secretary of State Stephen Biegun said in an online seminar on the sidelines of the annual U.S.-India Strategic Partnership Forum.

“There is certainly an invitation there at some point to formalize a structure like this,” he added.