The United States military is carrying out renewed strikes on Iran aimed at further degrading its ability to "threaten freedom of navigation in the Strait of Hormuz", after US President Donald Trump earlier threatened a "big attack" was coming.

US Central command announced the new strikes as an uneasy ceasefire continued to deteriorate between the two nations.

Iranian attacks followed by a U.S. response have been a repetitive cycle since President Donald Trump announced a ceasefire on April 7.