Iran attacked US bases in Jordan and Bahrain on Wednesday, the latest salvo in tit-for-tat strikes with the United States after the downing of a US helicopter over the Strait of Hormuz.

The worst bout of fighting between Washington and Tehran since their April 8 ceasefire has cast further doubt on US President Donald Trump's earlier claim that negotiations were in their "final throes" before reaching an enduring settlement to end the Middle East war.