While the exercises had been in the works for some time, they come one day after Iran Supreme Leader Ayatollah Ali Khamenei said a nuclear strategies recently stated by U.S. President Barack Obama were "atomic threats against Iranian people" and a Pentagon report that Iran would by 2015 have a missile that could reach the United States.
Many Western countries, led by the United States, are seeking U.N. Security Council sanctions against Iran, which they fear may be developing a nuclear weapons capability. Tehran said its nuclear program, of which Iranian leaders occasionally announce large expansions, is for peaceful purposes.
Obama recently issued a policy that severely limits when the United States might use a nuclear weapon but he also said there would be exceptions for "outliers like Iran and North Korea" because of suspected violations regarding nuclear proliferation.
Tehran saw that statement was provocation rather than an urging to do away with its nuclear program.
"How can the U.S. president make atomic threats against Iranian people? This threat is a threat against humanity and international peace and no one in the world should dare to articulate such words," Khamenei said in a speech Wednesday, as reported by the Fars news agency.
"We will not allow America to renew its hellish dominance over Iran."
Tehran is staging war games in and near the Persian Gulf, using ground, air and naval forces in a three-day exercise. An Iranian general said the exercise shows "Iran's strength and will against the threats of the enemies."