Iran's Revolutionary Guards rejected a US proposal for a crisis hotline.
The same day Iran carried out strikes on American bases in Bahrain and Kuwait.
Both Kuwait and Bahrain acknowledged the attacks.
US officials said the strikes targeted facilities used by American personnel.
The Iranian attack followed the hotline offer was made.
President Donald Trump warned that Iran's existence as a state will cease to exist.
He promised additional military action against Tehran.
Trump said any any new aggression would be met with decisive force.
The rejection of the hotline and the fresh attacks raise the danger of wider conflict.