WASHINGTON, July 2 (Reuters) – The Quad grouping of the United States, India, Japan and Australia called on Tuesday for the perpetrators of an Islamist militant attack that killed 26 in India-administered Kashmir to be brought to justice without delay. The April 22 attack sparked heavy fighting between nuclear-armed India and Pakistan in the latest escalation of a decades-old rivalry as India blamed it on Pakistan, which denied responsibility while calling for a neutral investigation. The U.S. State Department issued, a joint statement by the foreign ministers of the grouping, who met in Washington, but stopped short of naming Pakistan