Representatives from participating countries met for informal talks at the Waldorf-Astoria Hotel in preparation for official negotiations on the accord due to resume in July in Bonn, Germany.
Although Richardson will not be an official representative of Washington, White House administrators have consulted closely with him in preparation for the trip, CNN learned.
In the meantime, he said an assembly government emergency planning official inside the Cobra committee was providing regular updates, and Wales had already carried out an exercise in preparation for just such an attack.