Iran on Wednesday is expected to announce it is partially withdrawing from the nuclear deal it struck with world powers, a year to the day that President Donald Trump pulled the U.S. from the accord.

John Bolton said the U.S. wants to send a message that “unrelenting force” will meet any attack on U.S. interests or those of its allies.

The U.S. is engaged in a campaign to halt Iran's ballistic missile program and weaken its regional influence.