'BRING IT ON...: Iran Accepts Trump's Strike Challenge, Warns US Of 'Regret-Inducing Response'. Tensions between the United States and Iran are intensifying after sharp public exchanges between U.S. President Donald Trump and Iranian leaders. Trump warned of overwhelming military action if Tehran advances its nuclear or missile capabilities, while Iran’s president and senior officials vowed a severe response to any aggression. Tehran insists its missile program is defensive and non-negotiable, r