Dec 11 (Reuters) - A top Iranian military official warned on Saturday of a "heavy price" for aggressors, state media said, after a report of U.S. and Israeli plans for possible military drills to prepare for strikes against Iran"s nuclear sites if diplomacy fails. "Providing conditions for military commanders to test Iranian missiles with real targets will cost the aggressors a heavy price," Nournews, affiliated with Iran"s top security body, said on Twitter, citing an unnamed military official. A senior U.S. official told Reuters on Thursday that U.S. and Israeli defense chiefs were expected to discuss possible military exercises that would prepare for a worst-case scenario to destroy Iran"s nuclear facilities should diplomacy fail and if their nations" leaders request it. read more